[aggregate] Settings that control individual, or groups of, checks

[Nytelife26]

Relevant issues

Supersedes #139, #729, #1091, #1367.

Brief

For a long time, we have been requested to allow the fine-grained control of individual checks within a module. Prof. Suchow also suggested making groups of checks, depending on the context in which they are useful.

The latter is largely aided by the categorisation system as it stands, but it would be useful to have standard rulesets too, as is the case in other linters.

To-do

• Create groupings of checks.
• Facilitate the control of individual checks. Resolved in feat: implement check registry #1396, and will be implemented in the next release.