Fix copying integration assets
Created by: lguychard
Copying of native code host integration assets to /ui/assets
(which
allows them to be served by the Sourcegraph instance) was broken in
https://github.com/sourcegraph/sourcegraph/commit/d5bb53fb4db4ecb9b1b81724df314983ad6da1ee
Reported in https://sourcegraph.slack.com/archives/CNC4YAL1E/p1576263875005300?thread_ts=1576262866.004000&cid=CNC4YAL1E
This fixes it by removing the gulp tasks for copying the integration assets,
and instead doing the copy directly in browser/scripts/tasks.ts
.
Having separate copy tasks in the build script and in a gulpfile was awkward,
and has led to this same bug happening before.
Also adds a regression test to verify that all native integration assets are indeed served by the Sourcegraph instance.