Decouple wiki, snippets, designs and project repostory storage location
## Problem to solve
All Git repositories associated with a project are currently stored on the same Gitaly storage. However, this may not be optimal from a cost/performance perspective. For example it may be possible to store all these repositories on HDD storage at no significant performance penalty.
## Further details
## Proposal
Allow Git repositories to be rebalanced independently from a storage perspective.
## Links / references
issue