Add metadata/patch stripping to matrix version tag renderings

[ianpittwood]

I think we should specify the example without the build number.

    version: "2026.05.1"

Originally posted by @bschwedler in posit-dev/images-workbench#94 (comment)

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Regular image versions can use the {{ Version |stripMetadata }} template pattern to create a tag with the version metadata stripped off. Since matrix versions typically have compound version names (ex. R4.6.0-python3.13.13), we cannot apply the same template pattern to them and expect a clean result.

To implement this functionality, we would need to alter at least one of:

• How dependency names are passed into the compounded version name
• Use regex to trim patches/metadata off of versions in a compounded string
• Fundamentally change tag pattern structure for matrix versions so we could use a pattern like {{ '-' | join(component_versions | stripMetadata) }}