move the device test out of the AppModuleConnections test into its own executable and split it into a feeding and a consuming part

Split the SCALAR_ACCESSOR macro into SCALAR_OUTPUT and SCALAR_INPUT to prevent output accessors to be created in poll mode (which makes no sense). Since some tests were using this, now instead a DeviceAccessor in poll mode is used for these tests.

move the testTwoScalarPollPushAccessors into its own executable, which will contain all tests of illegal combinations

- all supported types
- check asynchronous behaviour
- check multiple consumers