fix(bump): harden prerelease and releaseAs behaviour

[cgatt]

This PR fixes a number of bugs identified with the bump behaviour:

• When passing a version with build metadata via either --release-as or through the prebump task, said build metadata is stripped

  > npx commit-and-tag-version --skip.tag --skip.commit --release-as 1.2.3-prerelease.0+build.info.123
  ✔ bumping version in version.txt from 1.1.0 to 1.2.3-prerelease.0
  ✔ outputting changes to CHANGELOG.md

  The use case for this is using versions from another tool, e.g. absolute-version
• When passing an invalid version to --release-as or any non-version string from the prebump task, the new version was being output as null
• When setting both --release-as and prerelease, the version could be set incorrectly. e.g:

  Current version: 99.0.0-prerelease.0
  Run command: npx commit-and-tag-version --skip.tag --skip.commit --release-as 100.0.0-prerelease.0 --prerelease prerelease
  Resulting version: 99.0.0-prerelease.1
  

• Added clearer errors for invalide/undefined cases, such as an invalid --release-as or conflicting prerelease identifiers between --release-as and --prerelease

BEGIN_COMMIT_OVERRIDE
fix: allow bump task to handle versions with build metadata
fix: handle invalid versions passed to releaseAs
END_COMMIT_OVERRIDE

[TimothyJones]

Thanks so much for this! One small correction and some optional suggestions. Assuming the build passes, I'll get this in and released once you've made any adjustments you'd like to.

[cgatt]

Let me know if there's any further changes you'd like, but I'm happy with this PR if you are :)

[TimothyJones]

Thanks @cgatt ! Releasing in 11.2.4.