PEP 621: Migrate .coveragerc and .mypy.ini into pyproject.toml (#23089)

https://peps.python.org/pep-0621

Migrate settings from `.coveragerc` and `.mypy.ini` into
`pyproject.toml` using [ini2toml](https://pypi.org/project/ini2toml) to
do the file conversion and running
[pyproject-fmt](https://pypi.org/project/pyproject-fmt) to format the
results.
```bash
ini2toml .mypy.ini > pyproject.toml
ini2toml .coveragerc >> pyproject.toml
pyproject-fmt pyproject.toml
git add pyproject.toml
git rm .coveragerc
git rm .mypy.ini
```

Author: cclauss

.coveragerc

@@ -0,0 +1,35 @@
+[tool.coverage.run]
+source = [ "." ]
+omit = [
+  "./test/*",
+  "./third_party/*",
+  "./tools/emcoverage.py",
+  "test.py",
+]
+
+[tool.mypy]
+mypy_path = "third_party/,third_party/ply,third_party/websockify"
+files = [ "." ]
+exclude = '''
+(?x)(
+cache |
+third_party |
+conf\.py |
+emrun\.py |
+site/source/_themes/ |
+tools/scons/site_scons/site_tools/emscripten/__init__\.py |
+site/source/get_wiki\.py |
+test/parse_benchmark_output\.py
+)'''
+
+[[tool.mypy.overrides]]
+module = [
+  "tools.create_dom_pk_codes",
+  "tools.webidl_binder",
+  "tools.toolchain_profiler",
+  "tools.filelock",
+  "tools.find_bigvars",
+  "leb128",
+  "ply.*",
+]
+ignore_errors = true

.mypy.ini

@@ -7,7 +7,7 @@
 flake8==5.0.4
 flake8-bugbear==22.9.23
 flake8-unused-arguments==0.0.11
-coverage==5.5
+coverage[toml]==5.5
 mypy==0.971
 types-requests==2.27.14
 unittest-xml-reporting==3.1.0