Android: Assets collection logic

[souvlakias]

This makes the Jetcaster.wear sample functional (Repo)
Closes #6544

Collects the assets directory from dependencies and passes them to aapt2 link

[lefou]

Since #6486, we should be able to use build.example.testPort or PORT env variable.

mill/example/package.mill

Lines 255 to 262 in bc6f01a

	/**
	* Unique port for this example test module.
	* Each module claims a port by incrementing the shared counter.
	* This ensures each example test gets a distinct port for parallel execution.
	*/
	val testPort: Int = portCounter.getAndIncrement()
	def forkEnv = Map("LANG" -> "C", "PORT" -> testPort.toString)

[souvlakias]

The caveat with build.example.testPorts logic, is that android emulators require an even port number between a certain range, in order to be visible to adb (https://developer.android.com/studio/run/emulator-commandline#common)

Note that if the port value is not even and is in the range 5554 to 5584, the virtual device will start but not be visible when you use the adb devices command, if the adb server starts after the emulator. For this reason, we recommend using an even console port number.

[vaslabs]

@souvlakias we can customise the testPort to follow the even port logic I think

[vaslabs]

try editing this

mill/example/package.mill

Line 143 in bc6f01a

trait ExampleCrossModuleAndroid extends ExampleCrossModule {

[lefou]

Does that really say the ports must be between 5554 and 5584? I'm not a native English speaker, so hard to tell, but it sound like it's just a suggestion to reduce impact by other assumptions.

For the even port number, you could acquire ports consecutively (run testPort repeatedly), until you get an even number, and then run it once more, to ensure the port + 1 is also reserved.

[souvlakias]

IIUC it is a suggestion yes, to catch the case of the adb server being started after the emulator. Thus, it does concern us since the adb server will run the first time we run any adb command which in our cases, happens after the calls of avd and emulator

[vaslabs]

We should also add this explanation and the link to the emulator port method