i32 comparisons often compare against constants, in order to implement
conditional branches. This CL optimizes such code by not loading the
constant into a register first, but directly emitting the comparison.
The code is shared for implementing {if} and {br_if} (and thereby makes
those two methods more readable).

R=thibaudm@chromium.org

Change-Id: I3f2f071a1c9e4b02c7368a2757bf4aae2920bd69
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3172765Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77008}