Add separators to context menu

[planger]

What it does

The number of menu items in the memory inspector's context menu already contributes to a convoluted list. In this change we add separators grouping those that are related to each other. To be consistent with other core context menu entires, I also added ... to those menu items, where additional input will be required.

How to test

This change only re-groups them to realize separators, so there is nothing more to test other than the grouping matches the expectations.

Review checklist

• [X] as an author, I have thoroughly tested my changes and carefully followed the contribution guidelines

Reminder for reviewers

• as a reviewer, I agree to behave in accordance with the code of conduct