Update the `WrapFuncInClassPass` pass so that, by default, the generated
method is named `operator()()` rather than `execute()`. This makes the
pass more generic, instead of catering to specific users expecting an
`execute()` method.
To preserve the original behaviour, add a new pass option to override
the method name: `func-name`. For example:
```bash
mlir-opt file.mlir -wrap-emitc-func-in-class=func-name=execute
```
Additionally, make a couple of small editorial changes:
* Rename `populateFuncPatterns` to `populateWrapFuncInClass` to make it
clear that the corresponding pattern is specific to the
`WrapFuncInClass` pass.
* Remove `// CHECK: module {` to reduce test noise.
For context, this change was proposed on Discourse:
* https://discourse.llvm.org/t/rfc-emitc-support-for-mlgo
10d80708d9