fix set self.filename when using crytic-compile

[rmi7]

When using CryticCompile (the "default"), self.filename will not be set, but is passed into each printer. Due to this, executing the inheritance-graph and call-graph printers will result in files with the default name, contracts and all_contracts, respectively. Instead of using the name of the Solidity file. Example on Migrations.sol:

INFO:Printers:Call Graph: all_contracts.dot
Call Graph: Migrations.dot

INFO:Printers:Inheritance Graph: contracts.dot

With the fix of this PR applied the result will instead be:

INFO:Printers:Call Graph: Migrations.sol.dot
Call Graph: Migrations.dot

INFO:Printers:Inheritance Graph: Migrations.sol.dot