[error panel] Add Hide Disabled Error list on Errors side panel

- Add Hide Disabled Error list on Errors side panel.
- Add Show Enabled Error list on Errors side panel.
- 4 Lines diff  :)


**Before:**
- I got 34783823 Lint errors I care of, but 0 PEP8 errors that I dont care.
- I Disable PEP8 on the Errors Panel.
- At any Screen Resolution it still using >50% screen space on the Errors panel, and its Empty !.

**After:**
- I got 34783823 Lint errors I care of, but 0 PEP8 errors that I dont care.
- I Disable PEP8 on the Errors Panel.
- At any Screen Resolution Lint Errors uses all available space on the Errors panel.
- PEP8 Empty Disabled error list is hidden freeing up space, the same applies for reverse case.


Brancho:  feature/hide_disabled_error_panel