chore: remove src/codeflash_core package

Remove the unused codeflash_core package and clean up the sdist include in pyproject.toml.

Author: KRRT7

pyproject.toml

@@ -104,7 +104,7 @@ tests = [
 ]
 
 [tool.hatch.build.targets.sdist]
-include = ["codeflash", "src/codeflash_core"]
+include = ["codeflash"]
 exclude = [
     "docs/*",
     "experiments/*",