graphics/openexr: bugfix update to 3.1.5

• Add backwards-compatibilty flags to the core library to match original behavior of the the c++ library. Fixes reading of certain files by the new core.
  • Documentation refers to primary branch as "main"
  • Update the CI workflow matrix to VFX-CY2022

Specific OSS-fuzz issues addressed:

• OSS-fuzz 46309 Heap-buffer-overflow in Imf_3_1::memstream_read
• OSS-fuzz 46083 Out-of-memory in openexr_exrcheck_fuzzer
• OSS-fuzz 45899 Integer-overflow in internal_exr_compute_chunk_offset_size
• OSS-fuzz 44084 Out-of-memory in openexr_exrcheck_fuzzer

MFH: 2022Q2