fix(cli): don't check sources directory existance during compilation

[shekhirin]

Motivation

Closes #2093

Solution

➜  mev-example git:(curve20220521) ls
cache  foundry.toml  interface  lib  out  README.md  remappings.txt  test

Before

➜  mev-example git:(curve20220521) forge test --fork-url $ETH_RPC_URL --fork-block-number 14811888 -vvv
Error:
no contracts to compile, contracts folder "/Users/shekhirin/Projects/mev-example/src" does not exist.
Check the configured workspace settings:
root: /Users/shekhirin/Projects/mev-example
contracts: /Users/shekhirin/Projects/mev-example/src
artifacts: /Users/shekhirin/Projects/mev-example/out
tests: /Users/shekhirin/Projects/mev-example/test
scripts: /Users/shekhirin/Projects/mev-example/script
libs:
    /Users/shekhirin/Projects/mev-example/lib
remappings:
    ds-test/=/Users/shekhirin/Projects/mev-example/lib/forge-std/lib/ds-test/src/
    forge-std/=/Users/shekhirin/Projects/mev-example/lib/forge-std/src/
    openzeppelin-contracts/=/Users/shekhirin/Projects/mev-example/lib/openzeppelin-contracts/contracts/
    src/=/Users/shekhirin/Projects/mev-example/src/
    test/=/Users/shekhirin/Projects/mev-example/test/

If you are in a subdirectory in a Git repository, try adding `--root .`

After

➜  mev-example git:(curve20220521) ../foundry/target/debug/forge test --fork-url $ETH_RPC_URL --fork-block-number 14811888 -vvv
[⠘] Compiling...
No files changed, compilation skipped

Running 1 test for test/MEV.t.sol:MEVSimulation
[PASS] testMEV() (gas: 2043432)
Test result: ok. 1 passed; 0 failed; finished in 133.98ms