feat: cache V executable to speed up subsequent runs

[cadamsdev]

Notable changes

• These changes cache the V executable when a version is specified.
• Added cache input so the user can turn off caching (caching is enabled by default)

Example

- name: Setup V
  uses: vlang/setup-v@v1
  with:
    version: '0.5.1'

First run (30 seconds)

Subsequent run (1 second)

Result
30x faster subsequent runs