Add exhaustive implicit capability declaration tests

Add 136 tests covering every capability with implicit declarations
from the SPIR-V grammar. Each test validates that declaring a
capability without its dependencies passes validation (since they
are implicitly declared).

Two tests (DescriptorHeapEXT, PushConstantBanksNV) are #[ignore]
because rspirv does not yet recognize these capability names.

Author: LegNeato