Fp16 conversions staging (#1864)

* Added unification of existing conversions test as preparation for cl_khr_fp16 adaptation

* Unified initialization procedures for conversions test.

* Completed unification of data structures to handle cl_khr_fp16

* Added support for selective launch of the test

* Added half support for test_conversions, work in progres (issue #142, conversions)

* Added more work on halfs support for conversions test (issue #142, conversions)

* Added cosmetic corrections

* Added more cosmetic corrections before opening draft PR

* Added corrections related to pre-submit windows build

* Added more pre-build related corrections

* Added pre-submit ubuntu build related correction

* Added more pre-submit related corrections

* Divided structures into separate source files (issue #142, conversions)

* Added more corrections related to presubmit check

* Removed redeclarations due to presubmit check

* Added more corrections related to presubmit check arm build

* Added cosmetic correction

* Adapted modifications from related PR #1719 to avoid merging conflicts

* fixed clang format

* Added corrections related to code review (cl_khr_fp16 suuport according to issue #142)

* Corrections related to macos CI check fail

* fix for unclear clang format discrepancy

* More corrections related to code review (cl_khr_fp16 for conversions #142)

---------

Co-authored-by: Ewan Crawford <ewan@codeplay.com>

test_common/harness/rounding_mode.h

@@ -42,10 +42,11 @@ typedef enum
     kshort = 3,
     kuint = 4,
     kint = 5,
-    kfloat = 6,
-    kdouble = 7,
-    kulong = 8,
-    klong = 9,
+    khalf = 6,
+    kfloat = 7,
+    kdouble = 8,
+    kulong = 9,
+    klong = 10,
 
     // This goes last
     kTypeCount