libwebsockets

BUGFIX: Fixed bug for installing test-apps for CMake.

Appending to the TEST_APP_LIST variable function did not work from within the create_test_app function (It would create a function scope variable with the same name and discard it). We instead need to use a macro for this.

The previous commit also removed the duplicate install for the test-apps (because we want all the install steps in one place in the file for clarity). That change made it obvious that the TEST_APP_LIST never gets populated.