Fix issues with typing tests introduced in the 5.2 merge.

My methodology for obtaining the list of possibly-problematic tests:

• Change Misc.Style.inline_code to stop inserting quotation marks. This removes noise between upstream and internal versions of tests. (The styling change to start using inline_code in a more widespread way is in 5.2.)
• See which tests have a diff between the merge base b532dff (in flambda-backend) and a workspace with the previous change applied.

I then classified the test diffs into these categories:

• Improvements pulled in from upstream
• Test files that are identical between the tip of the 5.2 merge and upstream main
• Changes that aren’t actually changes: the merge base already quoted some inline code, so my methodology found some false positives.

The remaining cases had actual problems. This PR fixes all problems I identified.

Problem #1: "Error: Don't know how to untag this type. Only int can be untagged."

Instances:

ocaml/testsuite/tests/typing-layouts-bits32/basics.ml
ocaml/testsuite/tests/typing-layouts-bits32/basics_alpha.ml
ocaml/testsuite/tests/typing-layouts-bits64/basics.ml
ocaml/testsuite/tests/typing-layouts-bits64/basics_alpha.ml
ocaml/testsuite/tests/typing-layouts-float32/basics.ml
ocaml/testsuite/tests/typing-layouts-float64/basics.ml
ocaml/testsuite/tests/typing-layouts-word/basics.ml
ocaml/testsuite/tests/typing-layouts-word/basics_alpha.ml
ocaml/testsuite/tests/typing-layouts/erasable_annot.ml

The merge introduced a new assumption from upstream (#12375) that a type that Typeopt thinks is immediate must have its lowest bit set to 1. But, internally, Typeopt also thinks of unboxed types like float# and int# as immediate. This is strange, and allowed programs like these to pass type-checking:

external blah : (float# [@untagged]) -> unit = "..."

@ccasin and I decided to check whether the sort of the type in question is Value as an additional criteria for @untagged.

Problem #2: Extra diff

There were a few issues where chunks of code were duplicated. I deleted the duped tests. See the commit messages for why.

Instances:

ocaml/testsuite/tests/typing-local/local.ml
ocaml/testsuite/tests/typing-modes/portable-contend.ml
ocaml/testsuite/tests/typing-layouts-float64/parsing.ml

Problem #3: Wrong location in expect tests

A failure to map over all locations in ast_mapper.ml meant that a location was wrong in ocaml/testsuite/tests/typing-layouts/error_message_attr.ml.