This switches the {WasmGraphBuilder::GetExceptionValues} to use a proper
vector instead of the deprecated {Buffer} method. This also addresses a
TODO about missing landing pads for the above affected method.

R=clemensb@chromium.org

Change-Id: I33ba7d712a00f2a284ec159a501bcd90e02a3a51
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1859620
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64276}