feat(ui): add strings list view pane

[tim21-f0]

This change adds a new "Strings List" pane which can be found under View -> Strings List.

On opening the new pane, a background task is initiated to search for all smali strings.

The pane has the following:

• A table of the found strings, the left column contains the string and the right column contains the references in the code where it is found.
• On double clicking one of the references the user is navigated to the code location in the main UI's code area.
• Results can be sorted lexicographically.
• Results can be filtered by string (literal and regex), package and minimum string length.