Test #9066 in th/T9066
Fix #9066.

When splicing in a fixity declaration, look for both term-level things
and type-level things. This requires some changes elsewhere in the
code to allow for more flexibility when looking up Exact names, which
can be assigned the wrong namespace during fixity declaration
conversion.

See the ticket for more info.
Untabify template-haskell.
Remove unboxed Int# fields from NameFlavour (#9527)
Derive Generic for TH types (#9527)
Test #8100 in th/T8100
Fix #8100, by adding StandaloneDerivD to TH's Dec type.
Test #9064 in th/T9064
Fix #9064 by adding support for generic default signatures to TH.
Test #9204 in roles/should_fail/T9204
Fix #9204 by outputting extra info on boot file mismatch.

[skip ci] -- testsuite wibbles are in next commit
Testsuite wibbles due to #9204
Fix #9788 by giving `coerce` the right type.

No test case added, as the original mistake is just one level
up from a typo.
Test #9404 (typecheck/should_compile/T9404 and T9404b)
Testsuite wibble due to #9404

[skip ci]
Fix #9404 by removing tcInfExpr.

See the ticket for more info about the new algorithm. This is a small
simplification, unifying the treatment of type checking in a few
similar situations.