Topshim: Migrate to new location

Moving the topshim tests to a different directory.

Make topshim use mobly test runner.

Using `gd/cert/run` script to run the tests.

system/gd/cert/run_topshim is replaced by this commit.

Fix non clear target to not use dist which adds extra build overhead
time.

Heavily rely on async paradigm for topshim testing.

Bug: 230373381
Test: gd/cert/run --clean --topshim
Tag: #stability
Change-Id: I05e21ab8c4716dcb58570f2583c25915753cd6b0