v2.0 - Custom Git Args

Added Inputs for Git Command Arguments

New 'advanced use' inputs for git commands in the sync process:

• git_checkout_args
• git_fetch_args
• git_push_args
• git_log_format_args
• git_pull_args

Except for the log format, all logs are empty by default.
Thanks to @cognifloyd for working on this PR.

Moving to v2.0

Default values have been removed for upstream_branch and target_branch inputs. Set these explicitly in your workflows.