gitweb: Option for filling only specified info in fill_project_list_info

Enhance fill_project_list_info() subroutine to accept optional
parameters that specify which fields in project information needs to
be filled.  If none are specified then fill_project_list_info()
behaves as it used to, and ensure that all project info is filled.

This is in preparation of future lazy filling of project info in
project search and pagination of sorted list of projects.

Signed-off-by: Jakub Narebski <redacted>
Signed-off-by: Junio C Hamano <redacted>