extensions: support custom string as release version

For a long time, there has been confusion among developers regarding how versions work.

The fact that developers don't have control over version numbers didn't resonate well with many.

This MR aims to add a "version string" to provide developers more control while keeping the current system as a fallback and for internal references.

Internal versions will be shown as "revision" on review pages to prevent ambiguity.

fixes: #169 (closed)