feat: Move git command to a subcommand of bump.

[jaevans]

No description provided.

[Copilot]

Pull Request Overview

This PR reorganizes the git command by moving it as a subcommand under the bump command while retaining the old git command as a deprecated command on the root.

• Migrate the git command to be accessed via bumpCmd
• Introduce a deprecated git command on the root and add new tests for tag retrieval functionality

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

File	Description
cmd/root.go	Added subcommands for deprecatedGitCmd, bumpCmd, and SortCmd.
cmd/git_test.go	Introduced tests for getTagsStrings with valid and empty tag cases.
cmd/git.go	Created a deprecatedGitCmd and updated flag initialization.
cmd/bump.go	Updated the command hierarchy to register gitCmd under bumpCmd.

Comments suppressed due to low confidence (1)

cmd/git_test.go:134

• [nitpick] Consider renaming test functions to follow standard Go naming conventions (e.g., TestGetTagsStringsValidVersions) for improved readability.

func Test_GetTagsStrings_ValidVersions(t *testing.T) {