Make gsemver bump auto more configurable

[arnaud-deprez]

Is your feature request related to a problem? Please describe.

Currently gsemver bump [auto] uses:

• conventional commits convention to generate the next version.
• look for tags with v prefix to find the latest version.
• generate version with build metadata on non release branches

Describe the solution you'd like

A lot of project do not use these conventions but others such as:

• git flow kind of convention: eg. a fix should be done in bug/* branch, a feature in feature/*, a breaking change in major/* or so. While it's not possible in git to retrieve the original branch, you can leverage a merge commit that contains the name of that branch and configure regular expression to match it.
• some projects use different prefix or no prefix at all for their tags
• some projects prefer to use pre-release on non release branch such as most of the maven project with their -SNAPSHOT version.

Additional context

We may want to leverage go template to define the version format in non release branches for example to reuse the current branch name, the commit id, the number of commits from the latest tag, etc.

So this feature should probably be split into smaller issues.

Tasks

• Allow to match tag with or without v prefix Match tag with or without v prefix #16
• Allow to use different bump strategy per branch(es) in auto mode Allow to use different bump strategy per branch(es) in auto mode #17
• Use go template for build-metadata and pre-release Use go template for build-metadata and pre-release #18
• Add major-regex and minor-regex parameter Add major-pattern and minor-pattern parameter #23
• Allow usage of "empty" pre-release Allow usage of "empty" pre-release #25
• Use configuration files Use configuration files #20