Generate a default wrapper for device java_binary

Any device java_binary that doesn't have a specific wrapper must
have a main_class property, which is used to generate its default
wrapper. Otherwise its build should fail.

Bug: 250851599
Test: TestDeviceBinaryWrapperGeneration in java_test.go
Change-Id: Ice4c580bcfc1b92f95e217b39e984c55d25a3a02