This creates a .tq file in src/objects for each src/objects/*.h file
with Torque-defined classes and moves the object definitions and
corresponding helpers/macros there.
In addition, we create files convert.tq and cast.tq in src/builtins
to move the casts and conversions to.

Since Torque-generated .cc files end up as .o files in the same
directory, there cannot be two .tq files of the same name. Thus it
was necessary to rename src/builtins/arguments.tq and
src/builtins/string.tq to not clash with the new files in src/objects.

This is a mechanical change that only moves code.

Design doc: http://doc/1fh4OUMjQMnQdJm3aiAPXQUNdgbQugkRGdJzDh8hmyzk

Bug: v8:9861 v8:9810 v8:7793
Change-Id: I9c54cb50f32b9ae0fb41752199515133eb59ea5c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1910100Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64892}