Diverging syntax for captures inside brackets

[AntonLydike]

Failing tests:

• mlir/test/Dialect/SCF/transform-loop-fuse-sibling.mlir:16:62 ([[ASLICE:%.*]] = vector.transfer_read [[A]][[[IV]]], [[ZERO]])
• mlir/test/Dialect/MemRef/expand-realloc.mlir:18 ([[SUBVIEW:%.+]] = memref.subview [[NEW_ALLOC]][0] [[[CURR_SIZE]]] [1])
• mlir/test/Conversion/MemRefToLLVM/memref-to-llvm.mlir:491:60 Invalid substitution block, unknown format: [[[EXTRACT1O]]
• mlir/test/Target/Cpp/expressions.mlir:314:40 Invalid substitution block, unknown format: [[[VAL_2]]
• mlir/test/Conversion/TosaToSCF/tosa-to-scf.mlir:73:67 Invalid substitution block, unknown format: [[[ITER_VAR_0]]
• test/Dialect/Bufferization/Transforms/lower-deallocations.mlir:80:54 Invalid substitution block, unknown format: [[[C0]]
• mlir/test/Target/Cpp/global.mlir:37:30 Invalid substitution block, unknown format: [[[V1]]
• mlir/test/Dialect/NVGPU/optimize-shared-memory.mlir:19:45 Invalid substitution block, unknown format: [[[ldRow]]
• mlir/test/Target/Cpp/subscript.mlir:12:24 Invalid substitution block, unknown format: [[[I]]

[AntonLydike]

Fixed by #16