New text is moved over from BlinkGCDesign.md

Bug: chromium:1283934
Change-Id: I10a84c91a642e96c494d6e523d6d89059afaa1ca
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3366658Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78498}

Give a little bit of introduction to Oilpan and provide a few links to
navigate the project.

Bug: chromium:1056170
Change-Id: I4ef8c256c8de7932e3393017be6c58ba48ca45f2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3114141
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76457}

Bug: chromium:1056170
Change-Id: I71375a2ac8f4ac51de8b6c1899f7f146e4f107ec
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3099949
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76346}

"By my deeds I honor him. V8."

- Add basic build files for library and unittests.
- Integrate unittests also in existing V8 unittests for simplicity.

The CL also adds FinalizerTrait and unittests to allow building a
testing target that executes code.

FinalizerTrait is used to determine how managed C++ types are
finalized. The trait should not be overridable by users but needs to
be exposed on API-level to avoid including library-internal headers.

Bug: chromium:1056170
Change-Id: I64d91053410a17a7835e50547f58990625d2da28
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2108549Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66834}