remove unused VCSAnnotationWidget class

it's now done by the kate icon border
DocumentController: use VCSHelper class instead for showing VCS annotation

Previously, it had duplicated the code from VCSHelper.
VCS annotations: use proper colors for the foreground + background

Previously, the code selected a background color at random, used the
default foreground color, and made the bar partially transparent.
That made it look bright on bright themes and dark on dark themes but the
text contrast was very bad for dark themes.
Now it actually generates bright / dark opaque colors depending on the
theme, and also uses a bright / dark foreground color (for the text)
depending on the theme.

Needs latest kate, setting the foreground color was broken there.
executescript plugin: auto-configure launchers for known file types

For some known file types, e.g. python, ruby, and php, the script page
will pre-select the matching interpreter when you create a new one.
fix wrong signal name
Script lancher: allow creating configurations from project items

(see right click menu)
make configureLaunchFromItem work when the selected file is not open
executescript: use Script filter by default for launches from context menu
output widget: make selection work properly when filtering is enabled
Open the diff of a commit when clicking the annotation border