✨ Add raw methods for error and activity reporting by addons.

[jortel]

Add raw methods used by addons to report both errors and activity. The reason is to reduce the number of API calls when reporting large numbers.
For example, the addon.command package reports stdout/stderr for failed commands which can be hundreds (or thousands of lines). Calling Activity() hundreds of times result in hundreds of API calls.
Another example is the reported analyzer errors.

Another aspect is to formalize multi-line activity. This PR codifies the convention of:

- This is a list of:
- > One
- > Two
- > Three

and, simplifies the API.

The tackle2-addon command package will need to be updated once this merges to use RawActivity() for stdout/stderr. reporting.
The tackle2-addon-analyzer will need to updated to use both methods in select places as well.

[jortel]

Moved Load() to adapter.Run(). Makes more sense.