This changeset include:
1. [prepare for migrate] move `cctest/compiler/value-helper.h`,
`cctest/compiler/c-signature.h`, and `cctest/compiler/call-tester.h` to
`test/common` directory because both `test-codegen` and a lot of cctest file
include it.
2. [prepare for migrate] separate the tester helper part of `test-codegen`
into a new `codegen-tester` file.
3. finally, migrate test-codegen.cc to `codegen-unittest.cc`

Bug: v8:12781
Change-Id: Ia2f52c1d3b6b62501066dc1c4308a2c09d699e92
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3831146Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82630}