feat(perf): use native assertions (#514)

* Update Vm.sol

* Drop DSTest and use native cheats

* fix ci

* Add abiencoder pragma to StdAssertions

* Add DSTest items

* fail and failed

* rm assertions tests

Author: klkvr

.gitmodules

@@ -217,7 +217,7 @@ contract Bar {
 
 ### Std Assertions
 
-Expand upon the assertion functions from the `DSTest` library.
+Contains various assertions.
 
 ### `console.log`