Integrated: 8260681: Lanai: Refactor MTLBlitLoops.m, common.h, shaders.metal

[Alexey Ushakov]

Moving common.h, shaders.metal to better place, remove format field from MTLRasterFormatInfo structure

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Commit messages:
 - 8260681: Lanai: Refactor MTLBlitLoops.m, common.h, shaders.metal

Changes: https://git.openjdk.java.net/lanai/pull/168/files
 Webrev: https://webrevs.openjdk.java.net/?repo=lanai&pr=168&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8260681
  Stats: 11 lines in 5 files changed: 0 ins; 1 del; 10 mod
  Patch: https://git.openjdk.java.net/lanai/pull/168.diff
  Fetch: git fetch https://git.openjdk.java.net/lanai pull/168/head:pull/168

PR: https://git.openjdk.java.net/lanai/pull/168