fixes#2140
Adds testing for SPIR-V 1.5 features:
* Adds a test for bitcasts between pointers and vectors of integers.
Note, SPIR-V 1.5 only supports bitcasts to vectors of two 32-bit
integers. Therefore, the SPIR-V 1.5 behavior will only be exercised on
devices with 64-bit pointers. The test will run on devices with 32-bit
pointers, but will instead bitcast to scalars.
* Adds a test for OpGroupNonUniformBroadcast with a dynamic index. Note,
this is not an exhaustive test, and only unsigned integer types are
tested, to avoid duplicating testing for cl_khr_subgroup_ballot.
* basic SPIR-V 1.3 testing support
* updated script to compile for more SPIR-V versions
* switch to general SPIR-V versions test
* update copyright text and fix license
* improve output while test is running
* check for higher SPIR-V versions first
* fix formatting
