Add TOSA-to-Linalg lowering pattern tests for elementwise

As detected [here](https://github.com/llvm/llvm-project/pull/220916#issuecomment-5538963626), there doesn't seem to be any elementwise tests for TOSA to Linalg, since no test had to be changed in the series.

Should be trivial to generate a repeat test for every elementwise operation from TOSA to Linalg upon a conversion pass.

Locate the TOSA-to-Linalg conversion pass and its existing pattern tests, then inspect how elementwise operations are represented there. Add repeat coverage for each elementwise operation and run the relevant conversion tests; done means the tests exercise the lowering without requiring changes to the lowering itself.

Written by the indexing model from the issue text.