Debugger: Minor tweak to enumeration editor.

- Don't return result of SelectOptionFor(). It's possible to attempt
to edit an enum value that hasn't yet been initialized, in which case
its current value might not map to any of the defined enumerations, and
the resulting error would prevent editing from being allowed.

Debugger: Flesh out option-based value editors.

TableCellOptionPopUpEditor:
- Add virtual hook for retrieving the final selected value. Implement
accordingly in Bool and Enumeration editor subclasses.
- Implement calling the edit completion hook upon value changes.

Debugger: Add table cell editors for various value types.

TableCell{Bool,Enumeration}Editor:
- OptionPopUp-derived editors for their respective value types.

TableCellIntegerEditor:
- TextControl-derived editor for integer values that validates inputs
based on the target integer size and type.

Not actually used yet, but together with the previous changes, these lay
the groundwork for the remaining part of #9708.

Debugger: Minor tweak to enumeration editor.

- Don't return result of SelectOptionFor(). It's possible to attempt
to edit an enum value that hasn't yet been initialized, in which case
its current value might not map to any of the defined enumerations, and
the resulting error would prevent editing from being allowed.

Debugger: Flesh out option-based value editors.

TableCellOptionPopUpEditor:
- Add virtual hook for retrieving the final selected value. Implement
accordingly in Bool and Enumeration editor subclasses.
- Implement calling the edit completion hook upon value changes.

Debugger: Add table cell editors for various value types.

TableCell{Bool,Enumeration}Editor:
- OptionPopUp-derived editors for their respective value types.

TableCellIntegerEditor:
- TextControl-derived editor for integer values that validates inputs
based on the target integer size and type.

Not actually used yet, but together with the previous changes, these lay
the groundwork for the remaining part of #9708.