Patch empty implicit parens on error recovery

[som-snytt]

Offer a rewrite for an erroneous application f() where the parameter list is implicit and a parameter lacks a default arg.

This was never official syntax, but was accepted from 3.3.4/3.4.2 due to a bug. The rewrite is for 3.7-migration, using the existing MigrationVersion.ImplicitParamsWithoutUsing, since that is a similar bit of syntax.

Fixes #22792

[som-snytt]

Requires a tweak: an implicit param list is not supplied implicitly if an arg list is present (but defaults may be supplied in the explicit application). It must not continue implicit application when rewriting.

Ha, in other words, canApplyImplicits should be false not true. I knew it had to be one of the two.

[som-snytt]

Added a test case for rewrite of Foo()() to Foo() instead of Foo().apply. That is a "big TODO".