Add ccache in all coreboot configs

[tlaurion]

Added in test builds for tpm1/tpm2 and life changing when calling inject_gpg make step. Would be really beneficial for all CircleCI builds reusing level 2 (coreboot module didn't change) + level 3 caches (no module def changed)

[saper]

Would that be possible to make ccache support optional (for example only if ccache is present, or as a switch)? I was a bit surprised to find it is a config file option... Normally one just updates CC/CXX environment variables...