Flag to enable/disable skipMergeCommits behavior for Git CLI and JGit

### New feature, improvement proposal

This feature request is to add the ability to skip the --no-merges behavior that was introduced in this commit:
https://github.com/apache/maven-scm/pull/193/files#diff-54686f353f1a0410c924cc017f740c8b003de6770b46beddab45f48a30644a3dR66

This feature request is in response to @kwin's comment in Nov 5, 2024 in this buildnumber-maven-plugin issue:
https://github.com/mojohaus/buildnumber-maven-plugin/issues/229#issuecomment-3419928452, indicating a new "skipMergeCommits" parameter would be needed, similar to the revision length parameter here: https://github.com/apache/maven-scm/blob/7f0b12ae405807ba42851681ca0899861af617af/maven-scm-providers/maven-scm-providers-git/maven-scm-provider-gitexe/src/main/java/org/apache/maven/scm/provider/git/gitexe/command/info/GitInfoCommand.java#L97.

Start with maven-scm-providers/maven-scm-providers-git/maven-scm-provider-gitexe/src/main/java/org/apache/maven/scm/provider/git/gitexe/command/info/GitInfoCommand.java and trace the existing revision-length parameter and skipMergeCommits behavior. Compare the Git CLI and JGit implementations, then verify that the new parameter is available and respected by both providers.

Written by the indexing model from the issue text.