Reorganize docs on typed classes

Use subsections and put the special forms first
Expand on docs for TR class init/init-rest args
Temporarily disable TR class unit test

This unit test is broken due to an issue with using
the : form for external names in classes. Since : checks
if the id is bound, it doesn't work if there is an internal
name different from the external name (since only the
internal one is in scope in the class body).

Haven't decided whether to put annotations on internal
identifiers instead or to not run the check for class
member names.
Fix type for first argument of dynamic-place

Closes PR 14363
Adjust type variable syntax for typed classes

This makes it consistent with other forms like the
new `lambda` form.
Support set-field! in Typed Racket
Move typed class unit tests into a separate file

Export some helpers from typecheck-tests in a submodule
Make typed case-lambda methods work
Add more class/object functions to TR base-env
Fix static contract generation for method case->s
Fix DrRacket's insert-large-letters

This is a temporary fix in the sense that the typed/mred
wrapper that this relies on is incomplete. Once the typed
racket/gui bindings are merged, a more complete
insert-large-letters will be checked in.

Closes PR 14362
add a test case to make sure 'Insert Large Letters' doesn't crash
always show the memory use and the () status indicators in drracket's status line
fix careless error (apologies future git bisecters)
update drracket HISTORY.txt
Make module reader not return negative span when port location changes.
Make TR optimizer tests reset the port line counting.

This means new logging lines should not change the numbering of all existing
logs making diffs much cleaner.
Add delays to unboxed let to avoid optimizing twice.
add 'simple-root' for students to use in test suites that call gc:cons
docs typos