retrieve annotations for KSType from KotlinType instead of KSTypeReference

[neetopia]

fixes #985

several open questions:

• defining annotations origin for KSType is tricky, as type is not part of source code. with this PR actually all annotation origins from KSType becomes library, which I actually found more meaningful, but this can be breaking change.
• since KotlinType.annotations contains the full picture of the actual annotations of a kotlin type, the annotations parameter in getKSTypeCached is no longer necessary, might want to clean up in a future patch.

[ting-yuan]

IIRC the first point you mentioned is the reason why the annotations are passed in. Another reason is that it was a (premature) optimization. To keep the behavior untouched, there are two approaches:

1. Fix call sites of getKSTypeCached.
2. Try to find PSIs for those annotations.

[neetopia]

sounds good, updated to not add from descriptor for annotations with actual source.