Improve validation of config values

[elopez]

Describe the desired feature

We should improve validation of some config values and alert the user. For example:

• deployContracts / deployBytecodes lets you deploy contracts on the precompile address space (0x1 ... 0xA) but that is not possible
• contractAddr can possibly also be set to those addresses
• sender / psender might also be set to those addresses (this is potentially fine though)
• function filters lets you have potentially invalid signatures (eg with spaces)

[gustavo-grieco]

We also need some validation for the verification and exploration mode. We could have a function that enforces constraints in Env