* chore: shared builder constants etc
* pretty-print the shared unknown builder error
* update builder impls to use shared defs and validators
* error and docs text formatting
* include static default short names
* comment updates and typos
* docs paths
* use the constants for the in-package builder defaults
* use builders.All but with caviat
Tekton pipeline runs now use the same logic for determining default builder image as a local buildpack build.
In order to implement varying build strategies (s2i vs buildpacks), we were unable to rely on hard-coded builder images. These defaults were moved in-code, with builders defined in func.yaml being an optional manual overrdide. This PR updates the Tekton deployment process to rely on this defaulting logic, rather than require the func.yaml override (which would preclude a Function from being able to be built using other strategies).
Luke Kingland
Zbynek Roubalik
Zbynek Roubalik