nvk: Support VK_KHR_multiview

Current CTS results for `dEQP-VK.multiview.*:

  Passed:        406/505 (80.4%)
  Failed:        0/505 (0.0%)
  Not supported: 99/505 (19.6%)
  Warnings:      0/505 (0.0%)
  Waived:        0/505 (0.0%)

There are currently no CTS tests available to test multiview support for:

CmdDrawIndirectCount
CmdDrawIndexedIndirectCount
CmdDrawIndirectByteCountEXT