genpolicy: add --version flag

[Redent0r]

Add a --version flag to the genpolicy tool that prints the current version

Merge Checklist

• Followed patch format from upstream recommendation: https://github.com/kata-containers/community/blob/main/CONTRIBUTING.md#patch-format
  • Included a single commit in a given PR - at least unless there are related commits and each makes sense as a change on its own.
• Aware about the PR to be merged using "create a merge commit" rather than "squash and merge" (or similar)
• genPolicy only: Ensured the tool still builds on Windows
• genPolicy only: Updated sample YAMLs' policy annotations, if applicable
• The upstream-missing label (or upstream-not-needed) has been set on the PR.

Summary

Add --version flag

`
$ target/debug/genpolicy -v

Kata Containers policy tool (Rust): id: genpolicy, version: 3.2.0-azl0.genpolicy1, commit: ffc72e5
`

dev: instead of cargo build, we'd use LIBC=gnu BUILD_TYPE= make (cargo build still works, but you'll need to use LIBC=gnu BUILD_TYPE= make the first time at least to generate version.rs and not get a compile error)

release: instead of cargo build --release, we'd use LIBC=gnu make (Here we'll want to stick to LIBC=gnu make as this will embed the correct commit information to release binary)

Make build method is incompatible on Windows. For Windows releases:

• set src/version.rs with correct commit info
• cargo build --release

[sprt]

Also to update the release process in the wiki to bump the version number.

[Redent0r]

Just force pushed following changes:

• Added commit info to version
• Separated build and release recipes. Then we can use make/make build for dev and make release when doing release, which seems more straightforward than using a unified recipe
• Added license to Cargo.toml

[sprt]

A couple comments. Also shouldn't we rather create this PR upstream?

[Redent0r]

Addressed feedback and corrected commit message