[clang] Changes to produce sugared converted template arguments

[clang] Changes to produce sugared converted template arguments

Makes CheckTemplateArgumentList and the template deduction functions
produce a sugared converted argument list in addition to the canonical one.

This is mostly NFC except that we hook this up to a few diagnostics in
SemaOverload.

The infrastructure here will be used in subsequent patches
where we perform a finalized sugared substitution for entities
which we do not unique per specializations on canonical arguments,
and later on will be used for template specialization resugaring.

Signed-off-by: Matheus Izvekov <mizvekov@gmail.com>
Differential Revision: https://reviews.llvm.org/D133874