libgit-rs: add get_bool(), get_ulong(), and get_pathname() methods to ConfigSet#1977

ionnss wants to merge 1 commit intogitgitgadget:mastergitgitgadget/git:masterfrom

ionnss:add-rust-configset-get-boolionnss/git:add-rust-configset-get-boolCopy head branch name to clipboard