Option to select the SPIR-V Runtime Dispatcher

[jjfumero]

Description

This PR adds an option in the TornadoOptions to select which runtime we want as default to dispatch SPIR-V code.
By default. TornadoVM currently selects the OpenCL, but the user now can override this by using the following option:

• Use -Dtornado.spirv.dispatcher=opencl to select OpenCL as default.
• Use -Dtornado.spirv.dispatcher=levelzero to select LevelZero as default.

This is useful to pass, for example, all tests with another Runtime Dispatcher for SPIR-V.

$ make tests-spirv-levelzero 

$ make tests-spirv-opencl

Problem description

n/ a.

Backend/s tested

Mark the backends affected by this PR.

• OpenCL
• PTX
• SPIRV

OS tested

Mark the OS where this PR is tested.

• Linux
• OSx
• Windows

Did you check on FPGAs?

If it is applicable, check your changes on FPGAs.

• Yes
• No

How to test the new patch?

make BACKEND=spirv

tornado --jvm="-Dtornado.spirv.dispatcher=opencl" uk.ac.manchester.tornado.drivers.TornadoDeviceQuery --params="verbose"

tornado --jvm="-Dtornado.spirv.dispatcher=levelzero" uk.ac.manchester.tornado.drivers.TornadoDeviceQuery --params="verbose"

## If set a random value
tornado --jvm="-Dtornado.spirv.dispatcher=foo" uk.ac.manchester.tornado.drivers.TornadoDeviceQuery --params="verbose"

#We get an error

[mairooni]

LGTM

[stratika]

LGTM, just a minor suggestions to clarify the default option of the flag.