case_insentive flag on Bus Class

[fpessacg]

Hi, I'm using the library cocotbext-wishbone and I had some problems when using it with ghdl records.
When I track down the error, I found that when the library creates a WB master, it uses the class busDriver, and then the class Bus. When adding a new signal, the method checks the flag case_insensitive (default= True), to check if the signal exists. The problem is that this function does not support record signals, and no signal is created. Also, there isn't a warning telling that the signal was not found.
I add a flag case_insensitive=False in the creation of WB Master, and it works. But I think an update to this function, or at least a warning might be needed.

[alexforencich]

Sounds like this is a duplicate of #39