Align prank behavior to Foundry

[palinatolmach]

Follow up to #120 and #110.
Related: #124.

Based on a Slack discussion with @hjorthjort and @anvacaru: in Foundry, prank is not effective when the test contract calls a function that is defined in a contract that the test is inherited from. With Foundry, all tests in the following contract pass:

// SPDX-License-Identifier: UNLICENSED
pragma solidity >=0.6.2 <0.9.0;

import "forge-std/Test.sol";
import "forge-std/Vm.sol";
import "../src/timetravel/CallBreaker.sol";


contract PrankParent is Test {
  function parentFunction(address p) public {
    assertEq(p,msg.sender);
  }
}

contract External is Test {
  constructor(address p) {
    assertEq(p,msg.sender);
  }

  function externalFunction(address p) public {
    assertEq(p,msg.sender);
  }
}

contract PrankTest is PrankParent {

  function test_startP(address p) public {
    address sender = msg.sender;
    vm.startPrank(p);
    assertEq(msg.sender, sender);
    localFunc(sender);
    parentFunction(sender);
    External e = new External(p);
    e.externalFunction(p);
    vm.stopPrank();
  }

  function test_p(address p) public {
    vm.prank(p); External e = new External(p);
    address sender = msg.sender;
    vm.prank(p); assertEq(msg.sender, sender); e.externalFunction(p);
    vm.prank(p); localFunc(sender); e.externalFunction(p);
    vm.prank(p); parentFunction(sender); e.externalFunction(p);
    vm.prank(p); e.externalFunction(p);
  }


  function localFunc(address p) public {
    assertEq(p,msg.sender);
  }
}

In addition, vm.prank(x); vm.prank(x); causes a runtime failure in Foundry, while, in Kontrol, we insert a prank only if no other is active (source); this specific scenario is not handled, so the configuration would get stuck. We have a test for this here.

We should align prank-related behavior of Kontrol with Foundry.