Add edsc::Indexed helper struct to act as syntactic sugar

This CL adds edsc::Indexed.

This helper class exists purely for sugaring purposes and allows writing
expressions such as:

```mlir
   Indexed A(...), B(...), C(...);
   ForNest(ivs, zeros, shapeA, ones, {
     C[ivs] = A[ivs] + B[ivs]
   });
```

PiperOrigin-RevId: 229388644
2 files changed
tree: 0962d614f0bc42295ea857d32a6085b4b70a0792
  1. g3doc/
  2. include/
  3. lib/
  4. test/
  5. tools/
  6. utils/
  7. .clang-format
  8. LICENSE.TXT