processor_content_modifier: fix and enhance data type conversion

[edsiper]

As described in #10145, some data types conversion were wrong or just missing. This patch makes the proper fixes and extend to handle unsigned types.

e.g:

pipeline:
  inputs:
    - name: dummy
      dummy: |
        {
          "string_to_int": "-1",
          "string_to_uint": "1",
          "string_to_double": "0.2",
          "string_to_boolean": "true",
          "string_to_string": "hello",
          "int_to_string": 1,
          "double_to_double": 0.2,
          "int_to_boolean": 1,
          "int_to_int": -1,
          "uint_to_uint": 1,
          "int_to_double": 1,
          "boolean_to_string": true,
          "boolean_to_boolean": true,
          "boolean_to_int": true,
          "boolean_to_double": true
        }
      processors:
        logs:

          # convert string to int (negative value)
          - name: content_modifier
            action: convert
            key: string_to_int
            converted_type: int

          # convert string to int (positive value)
          - name: content_modifier
            action: convert
            key: string_to_uint
            converted_type: int

          # convert string to double
          - name: content_modifier
            action: convert
            key: string_to_double
            converted_type: double

          # convert string to boolean
          - name: content_modifier
            action: convert
            key: string_to_boolean
            converted_type: boolean

          # convert string to string
          - name: content_modifier
            action: convert
            key: string_to_string
            converted_type: string

          # convert double to double
          - name: content_modifier
            action: convert
            key: double_to_double
            converted_type: double

          # convert int to string
          - name: content_modifier
            action: convert
            key: int_to_string
            converted_type: string

          # convert int to boolean
          - name: content_modifier
            action: convert
            key: int_to_boolean
            converted_type: boolean

          # convert int to int (negative value)
          - name: content_modifier
            action: convert
            key: int_to_int
            converted_type: int

          # convert int to int (negative value)
          - name: content_modifier
            action: convert
            key: int_to_double
            converted_type: double

          # convert boolean to string
          - name: content_modifier
            action: convert
            key: boolean_to_string
            converted_type: string

          # convert boolean to boolean
          - name: content_modifier
            action: convert
            key: boolean_to_boolean
            converted_type: boolean

          # convert boolean to int
          - name: content_modifier
            action: convert
            key: boolean_to_int
            converted_type: int

          # convert boolean to double
          - name: content_modifier
            action: convert
            key: boolean_to_double
            converted_type: double

  outputs:
    - name : stdout
      match: '*'
      format: json_lines

Output:

bin/fluent-bit -c ../conf/convert.yaml | jq
Fluent Bit v4.0.0
* Copyright (C) 2015-2024 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

______ _                  _    ______ _ _             ___  _____ 
|  ___| |                | |   | ___ (_) |           /   ||  _  |
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   __/ /| || |/' |
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / / /_| ||  /| |
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V /\___  |\ |_/ /
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/     |_(_)___/ 


[2025/03/29 10:34:01] [ info] [fluent bit] version=4.0.0, commit=b0f3a63c87, pid=3947811
[2025/03/29 10:34:01] [ info] [storage] ver=1.5.2, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2025/03/29 10:34:01] [ info] [simd    ] disabled
[2025/03/29 10:34:01] [ info] [cmetrics] version=0.9.9
[2025/03/29 10:34:01] [ info] [ctraces ] version=0.6.2
[2025/03/29 10:34:01] [ info] [input:dummy:dummy.0] initializing
[2025/03/29 10:34:01] [ info] [input:dummy:dummy.0] storage_strategy='memory' (memory only)
[2025/03/29 10:34:01] [ info] [sp] stream processor started
[2025/03/29 10:34:01] [ info] [output:stdout:stdout.0] worker #0 started
{
  "date": 1743266042.566744,
  "uint_to_uint": 1,
  "string_to_int": -1,
  "string_to_uint": 1,
  "string_to_double": 0.2,
  "string_to_boolean": true,
  "string_to_string": "hello",
  "double_to_double": 0.2,
  "int_to_string": "1",
  "int_to_boolean": true,
  "int_to_int": -1,
  "int_to_double": 1.0,
  "boolean_to_string": "true",
  "boolean_to_boolean": true,
  "boolean_to_int": 1,
  "boolean_to_double": 1.0
}

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Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.