Mixed case request results in missing request parameters in generated code

Version: betterproto==2.0.0b3

Requests with capital letters in the name seem to cause an issue with constructing methods. The request parameters are not added to the method. e.g

proto file:
```
rpc TestCAPITALS(TestCAPITALSRequest) returns (TestCAPITALSResponse){}

message TestCAPITALSRequest{
string name = 1;
}

message TestCAPITALSResponse{}
```

generated class:
```
async def test_capitals(self) -> "TestCapitalsResponse":

request = TestCapitalsRequest()

return await self._unary_unary(
"/tumelo.transparency.v1.InstrumentPortfolioTransparency/TestCAPITALS",
request,
TestCapitalsResponse,
)
```
we would expect a `name` field in the request but it is not there

Start with the mixed-case RPC and request definitions shown in the issue, then compare them with the generated async method and request construction. Trace the code-generation path that turns the RPC and message names into the method, and confirm that the generated request preserves the name field. Done means the example method includes the request parameter while retaining the RPC path and response type.

Written by the indexing model from the issue text.