R1:67ea5a0b61c4

Search by full path in Owners

Summary:
Search tool currently allows only searching by substring which is useful.
But searching by the full path (for packages in which the path is contained) is
probably even more useful.

NOTE: I used a trick to perform the search by superstring.

Packages containing path '/' are found always which could seem strange but it is
correct after all.

Test Plan:
Search for /src/x/a.php. Found package with path /src/x/.
Search for /src/. Found package with path /src/x/.