Make BindSymbolicName the canonical form of a FacetValue wrapping the BindSymbolicName

[danakj]

If a BindSymbolicName is converted to type and then to its exact FacetType, we get a FacetValue wrapping the BindSymbolicName but providing no different information: it has the same witnesses and FacetType as the original BindSymbolicName. Yet it is a different constant value, creating multiple canonical forms with the same meaning. Now we make that FacetValue with the same FacetType as the BindSymbolicName it wraps evaluate back to the BindSymbolicName, making it the unique canonical form.

This makes the "shortcut" in convert for avoiding impl lookup when converting from FacetAccessType to FacetType in this exact scenario work the same as doing the full impl lookup.

[zygoloid]

New test looks good but I think theres'a bug to be fixed here too.

[danakj]

PTAL

[zygoloid]

Looks good, thanks! I assume the new test also passes with the shortcut removed now? [Edit: I see you mentioned that it does in another comment]