Allow specifying copts for different tools invoked by xctoolrunner

Xcode allows specifying some options (for e.g. `momc` or `mapc` or `ibtool` or `actool`) via various build settings (e.g. we rely on setting `--no-inverse-relationship-warnings` to keep builds quiet via `MOMC_NO_INVERSE_RELATIONSHIP_WARNINGS` in Xcode). Currently, the resource rules do no have a way to specify copts that should be given to the resource compiling tools, but it would be really nice if there was.

Start by tracing the resource rules and xctoolrunner entry point to see how resource-compiling tools such as momc, mapc, ibtool, and actool are invoked. Done means the resource rules can configure copts for individual tools, including options supplied through settings such as MOMC_NO_INVERSE_RELATIONSHIP_WARNINGS.

Written by the indexing model from the issue text.