[WebLayer] Add weblayer_support_apk to the all target

Make sure to build weblayer_support_apk on cq bots in
order to prevent compile/deps issues early on.

Note: the shell no longer directly depends on the
WebLayerSupport.apk, but the perf bots do.

Change-Id: I3956d8d6f12b82be8c08d7c86d476a5ade92c547
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1960148
Reviewed-by: Bo <boliu@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Tim Volodine <timvolodine@chromium.org>
Cr-Commit-Position: refs/heads/master@{#723872}

• BUILD.gn[diff]