Remove or replace links to examples that were removed or moved under
manual tests.
Replace code snippets that were quoting the now-missing examples.
Fix documentation of QSet::removeIf().
Fix typo in documentation macro: Unknown command '\examplecateogry'.
Add qtopengl, qtshadertools dependencies to Qt Widgets documentation
project to enable correct linking to those topics.
Mark all documentation sets in qtbase as free of warnings.
Pick-to: 6.6 6.5
Change-Id: I058cd5f2063aa933ea310bceff906f05422a7cb2
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>