In preparation for some workspace restructuring, I decided to scratch a
few itches of my own in the code:
* Change project's RuntimeInfo field to just Runtime, to match the
serialized name in JSON/YAML.
* Eliminate the no-longer-used Context and NoDefaultIgnores fields on
project, and all of the associated legacy PPC-related code.
* Eliminate the no-longer-used IgnoreFile constant.
* Remove a bunch of "// nolint: lll" annotations, and simply format
the structures with comments on dedicated lines, to avoid overly
lengthy lines and lint suppressions.
* Mark Dependencies and InitErrors as `omitempty` in the JSON
serialization directives for CheckpointV2 files. This was done for
the YAML directives, but (presumably accidentally) omitted for JSON.
9aedb234af