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

[lukehans]

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:
mojohaus/buildnumber-maven-plugin#229 (comment), indicating a new "skipMergeCommits" parameter would be needed, similar to the revision length parameter here:

maven-scm/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

Line 97 in 7f0b12a

private static int getRevisionLength(final CommandParameters parameters) throws ScmException {

.