Added support for reading the long git sha1 and the current git tag.

[haath]

Hello!

I have implemented three new methods.

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var longSha1: String = CompileTime.buildGitCommitShaLong();

Similar to buildGitCommitSha(), but returns the full sha1 instead of the shorter version.

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var tagDescr: String = CompileTime.buildGitTagDescription();

Returns the output of: git describe --tags

Will either be the current tag (e.g v1.0.2) or the latest tag with the short sha1 (e.g v1.0.2-104ad4e).

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var tag: String = Compiletime.buildGitTag();

Returns the output of: git describe --tags --exact-match

Will either be the current tag or null.