Refactor for preliminary Rust vendor image support

Refactors parts of CC to prepare for preliminary support for using Rust
static libraries in vendor images. Some previously private functions are
made public, and additional functions are added to LinkableInterface so
GetMakeLinkType can be passed a LinkableInterface.

Bug: 172525289
Test: m
Change-Id: I5fda48e79532fe9ceab255e18d910af58048a123