Fix pytest-cov crash (#1390)

The `pytest-cov` plugin is used to gather test coverage info, using the
`coverage` tool.
It suffers from a limitation where child processes created by tests do
not inherit the `coverage` configuration from `pyproject.toml` because
that file is not on the command line.
This limitation is described here
nedbat/coveragepy#512
With the introduction of LSP, we started encountering crashes when
collecting coverage data, because LSP launches a child process.
The solution is to move `coverage` configuration into a dedicated
`.coveragerc` file.

This PR does just that.

Fixes #1363

Co-authored-by: Guenia Izquierdo Delgado <[email protected]>

Author: ericvergnaud

.coveragerc

@@ -0,0 +1,15 @@
+[run]
+branch = true
+parallel = true
+omit =
+    src/databricks/labs/remorph/coverage/*
+    src/databricks/labs/remorph/helpers/execution_time.py
+    tests/resources/lsp_transpiler/lsp_server.py
+    __about__.py
+
+[report]
+exclude_lines =
+    no cov
+    if __name__ == .__main__.:
+    if TYPE_CHECKING:
+    def main()

pyproject.toml

@@ -131,21 +131,6 @@ ban-relative-imports = "all"
   "ARG001" # tests may not use the provided fixtures
 ]
 
-[tool.coverage.run]
-branch = true
-parallel = true
-
-[tool.coverage.report]
-omit = ["src/databricks/labs/remorph/coverage/*",
-  "src/databricks/labs/remorph/helpers/execution_time.py",
-  "__about__.py"]
-exclude_lines = [
-  "no cov",
-  "if __name__ == .__main__.:",
-  "if TYPE_CHECKING:",
-  "def main()",
-]
-
 [tool.pylint.main]
 # PyLint configuration is adapted from Google Python Style Guide with modifications.
 # Sources https://google.github.io/styleguide/pylintrc