Fixes to GrepOutputView toolbar
- fix crash when aborting grep jobs at startup by clicking on
"Clear Search History" (introduced in commit 42eb6bb62c28)
- correctly disable result navigation buttons (fixes crash
when clicking on "Collapse All" button for an empty result)
- change icons for "Collapse All" and "Expand All" (were marked as TODO)
Before:
{F3805931}
After:
{F3805930}