[feat]: Allow attestors to be run during multiple lifecycle states

[jkjell]

Today, attestors are limited to one run during one lifecycle stage. It will be useful to run the same attestor during different points to collect additional information.

Example: I'd like to run my git attestor as a pre attestor to catalog all of the files inputted to a command run. AND I'd like to run my git attestor as a post attestor to determine if anything modified versioned controlled files during the witness run.

I haven't completely scope the changes required for this but, for Witness we will at least need the ability to specific which attestor to run during which life cycle stage. Today you can only specific the attestor itself, with an implicit lifecycle state.