Make gaslimit and gasprice usable in tracecall

[area]

As it stands, the gasLimit and gasPrice parameters (albeit undocumented?) are not usable. This is because hardhat enforces command line parameters to be lowercase. When trying to use latest hardhat-tracer, and passing --gasLimit to tracecall:

Error HH310: Invalid param --gasLimit. Command line params must be lowercase.

But then when trying to make it lowercase:

Error HH305: Unrecognized param --gaslimit

This PR makes them lowercase. It also appears to work - when tracing a call with --gaslimit and providing much less gas than it needs, at the end of my call I get:

   [EXCEPTION] EvmError(reason: "OUT_OF_GAS")

as I would expect.

[zemse]

Thanks for the PR!