Do not try to find PSI element, but always use the IR element offsets
instead. This greatly simplifies test data because we don't need to have
custom PSI- and LT- based diagnostic ranges in every test, and K1/K2
behavior also is mostly the same.
The exact offset ranges are not as important for backend diagnostics, so
it's better to have K2+PSI and K2+LT behaving the same.
Descriptors are already supposed to be sorted in scopes. The problem is
that rendering descriptors for sorting takes a lot of time (~1.5% of
total compilation time of intellij with JVM IR), and simple heuristics,
like comparing by names first, don't fully help with it.
#KT-48233
- clashing JVM signature diagnostics should be reported in stable order
- drop tests for clashes vs package facades
- introduce box test for class named as old package facade
- fix some testData
- render the whole line where the error/warning points to, if any, and another
line with '^', like other compilers do
- lowercase diagnostic severity
- decapitalize the message if it doesn't start with a proper name