feat(cli): provide executable script for the package

[asopian]

Make the package to be executable from the CLI.
And allows transforming input from stdin or from a file (option -f).
Also allows jmespath expression to be given as param or from file (option -e).

Example:

1. Using stdin

echo '{"hello": "world"}' | jp "hello"    # Output: "world"

Assuming jp_input.json :

{
  "hello": "world"
}

And jp_query :

 hello

2. Using CLI parameters

jp -f jp_input.json -e jp_query   # Output: "world"

Later on this can be scripted or used with nodemon for continuous exploratory working with JSON transformation.
For example:

npx nodemon --watch jp_query.query --exec "jp -f jp_input.json -e jp_query.query > jp_output.json"

[springcomp]

I like the idea.

@asopian would that benefit from being written in TypeScript ?