Add configuration option to specify file patterns to ignore

[kaniini]

Presently kontext has a hardcoded policy to ignore .git directories. Planned enhancements to the Wolfi build system require .git to be present to allow for the source date epoch to be calculated based on the last commit to a package.

By changing Bundle to take a configured list of file/directory patterns to ignore, we can control whether .git is stored in a kontext or not.