Boxing visitor #1695: move the type-parameter-with-bounds->untrusted from declaration to tree visitor

Because the declaration is not the one causing issues, it's the call-sites outside of the scope
of those type parameters
Test for #1695: Sequential attribute instead of Sequence => incompatible types
AT #1695: allow subtyping for covariant TP in non-widening computation
AbstractTransformer/nonWidening #1695: ignore intermediate widening refining declarations

Since those will have a non-widening type anyways.
AbstractTransformer/nonWidening #1695: fix rules for subtyping and widening
Updated test .src for #1695: erasure/widening rules changed
More test .src changes for #1695: Sequential attribute instead of Sequence => incompatible types
Invocation #1695: use non-widening parameter type if there is one, in named invocations
Added second test for #1695: Sequential attribute instead of Sequence => incompatible types