Merge branch 'jt/grep-wo-submodule-odb-as-alternate'

The code to make "git grep" recurse into submodules has been updated to migrate away from the "add submodule's object store as an alternate object store" mechanism (which is suboptimal). * jt/grep-wo-submodule-odb-as-alternate: t7814: show lack of alternate ODB-adding submodule-config: pass repo upon blob config read grep: add repository to OID grep sources grep: allocate subrepos on heap grep: read submodule entry with explicit repo grep: typesafe versions of grep_source_init grep: use submodule-ODB-as-alternate lazy-addition submodule: lazily add submodule ODBs as alternates