Soroban metrics improvement

[jayz22]

Description

Resolves all the items in this checklist: https://github.com/stellar/stellar-core-internal/issues/236#issuecomment-1915049419

Most of them are just some naming and types change. There is one structural change:

A new SorobanLedgerMetrics was added in LedgerManager which tracks soroban resource usage per ledger across all soroban ops (invoke_host_fn, restore_footprint, extend_ttl), and publishes them to new metrics "soroban.ledger.xxx".

Checklist

• Reviewed the contributing document
• Rebased on top of master (no merge commits)
• Ran clang-format v8.0.0 (via make format or the Visual Studio extension)
• Compiles
• Ran all tests
• If change impacts performance, include supporting evidence per the performance document

[jayz22]

@MonsieurNicolas thanks for the review, and sorry about the confusion. Most of the confusion comes from "read" == both read and modified, and "write" == only modified, and "entry" == LedgerEntry which could be {ContractDataEntry, ContractCodeEntry}, and we also have "data" and "code" which are just those two variants.
I've cleaned up the wording of the entire section, hope that makes it clear now.

[graydon]

r+ fed81d0