Reorganize custom categorize exp simplification rules

[zliu41]

We introduce some category-theoretic rules like f . id = f when constructing expression in target category like mkCompose'. By nature, such expressions can be scattered here and there in conversion, so we want to have some centralized rule map and apply them systematically.

Acceptance Criteria:

have a consensus inside the team about the strategy

make a refactored function and rules map for the application of the rules

clear documentation of this step

(Extricated from https://kitty-hawk.atlassian.net/browse/SW-3371)