ValueParser: rename publicly exposed function names to indicate they are parsers

[smelc]

Changelog

- description: |
    ValueParser: rename publicly exposed function names to indicate they are parsers
    
    To adapt: prefix old function name by `parse` and everything should compile again.
# uncomment types applicable to the change:
  type:
  # - feature        # introduces a new feature
  - breaking       # the API has changed in a breaking way
  # - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
  # - refactoring    # QoL changes
  # - bugfix         # fixes a defect
  # - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

• Fixes Rename functions in ValueParser.hs, to indicate in the name they are parsers #673
• Most functions in ValueParser that have a -> Parser _ return type had nothing in their name indicating that they do so. Those functions' name now start with parse.

How to trust this PR

It's only renamings

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• Self-reviewed the diff

[smelc]

The third commit is optional, since it only concerns names that are not exposed.

[carbolymer]

❤️