fix: remappings structure as solc input

[antico5]

We are sending the remappings object to solc with absolute paths, e.g:

    "remappings": [
      "ds-test/=/home/.../projects/.../lib/forge-std/lib/ds-test/src/",
      "forge-std/=/home/.../projects/.../lib/forge-std/src/",
    ]

After this change, the remappings object is sent in the way they are declared, without transforming relative into absolute paths, e.g:

    "remappings": [
      "ds-test/=lib/forge-std/lib/ds-test/src/",
      "forge-std/=lib/forge-std/src/",
    ]

Closes #369

[antico5]

@kanej just checked and this one is good to go