Add optional `branch_name_include_pattern` parameter to `snapshot_get_branches`,
if provided only branches whose name contains the given pattern will be
returned.
Add optional `branch_name_exclude_prefix` parameter to `snapshot_get_branches`,
if provided branches whose name starts with the given pprefix will not be
returned.
The purpose is to add branches filtering in `swh-web`. As that feature
could be useful elsewhere, I thought adding it at `swh-storage` level
was better than implementing it client side each time it is required.
Related to T2782