Improve BuildVersion verification and local checks in krel build

[puerco]

What type of PR is this?

/kind cleanup
/kind feature

What this PR does / why we need it:

This PR improves the input validation in krel release by introducing the following changes:

1. The release.IsValidReleaseBuild() function now enforces the versionBuildRE regexp to check the build version when it contains a plus sign.
2. This same function is now used in the options validation in anago in addition to the SemVer parsing check.
3. Finally, when invoking a command that would result in a cloud build Job, krel release will now perform a local validation of the options before running.

While the options are checked during the release process, double-checking them saves the release manager time in case of an error and resources by avoiding the execution of a job destined to fail.

Which issue(s) this PR fixes:

Stops a recurring problem with input encountered again during the v1.22.0-alpha.1 cut (kubernetes/sig-release#1547)

Special notes for your reviewer:

Does this PR introduce a user-facing change?

- `krel release` will now check its inputs locally before submitting a GCB job.
- The `release.IsValidReleaseBuild()` function will now do a better validation of the BuildVersion option.
- Options in krel now perform a better check of the BuildVersion string in addition to parsing it as SemVer

[puerco]

/milestone v1.22

[cpanato]

/priority important-soon

[cpanato]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cpanato, puerco

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• cmd/krel/OWNERS [cpanato,puerco]
• pkg/OWNERS [cpanato,puerco]

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