Fix: replace `build_info` with protocol version for `ligo version`

Motivation and Context

Related Issues: #1500 (closed) #1502 (closed)

Description

By default, a build_info is generated by Command_unix. This MR overrides this build_info with a string describing current protocol.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Performance improvement (non-breaking change that improves performance)
• None (change with no changelog)

Changelog

Before

$ ligo version
((build_time(1970-01-01 01:00:00.000000+01:00))(x_library_inlining false)(portable_int63 true)(dynlinkable_code false)(ocaml_version"")(executable_path"")(build_system""))            
0.55.0

After

$ ligo version
Protocol built-in: lima
0.55.0

Checklist:

• Changes follow the existing coding style (use dune @fmt to check).
• Tests for the changes have been added (for bug fixes / feature).
• Documentation has been updated.
• Changelog description has been added (if appropriate).
• Examples in changed behaviour have been added to the changelog (for breaking change / feature).