Instead of always using {AssemblerBase::kMinimalBufferSize}, this CL
computes the expected code size per function compiled with Liftoff, and
uses that size to allocate the initial assembler buffer. This saves
reallocations especially for big functions.

R=jkummerow@chromium.org

Change-Id: I0031033c6be986f9d0d7bb10db0d213669044603
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1910951Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64938}