fix(gui): Improved Exclude tab in Manage profiles dialog with SSH encrypted profiles

[buhtz]

The Exclude TAB in Manage profiles improved in context of SSH encrypted mode (using encfs). As explained in #1618 some exclude patterns are not functional with EncFS so they are ignored and visually disabled.

• The items fore and background ColroRole now try to imitate disabled state. But they are still selectable (e.g. to delete them).
• That items now have a tool tip to explain why they are disabled.
• warning message on top of the exclude list:
  • improved wording
  • Examples in brackets now using monotyp font (via <code> tag in richtext mode)
• Slightly refactoring of some code.

Wouldn't give this an extra changelog.

Close #1618

[buhtz]

From maintainer to maintainer: I discovered this cool suggestion-feature.

[aryoda]

From maintainer to maintainer: I discovered this cool suggestion-feature.

I can't see this button. In which context did you see it? In issue comments, PR comments...?

[buhtz]