Remove the examples/ directory. (#11100)

We now have example repos instead.

A few tests were using some example code, so it was moved
under testprojects/ for now.

Also applies a couple of unrelated style tweaks, and adds
a python_requirement_library for the pycharm remote debugging
client, to make remote debugging easier, as explained in
https://www.pantsbuild.org/docs/python-test-goal#running-tests-interactively.

[ci skip-rust]

[ci skip-build-wheels]

3rdparty/python/BUILD

@@ -10,3 +10,10 @@ python_requirements(
     "setuptools": ["pkg_resources"],
   }
 )
+
+# Useful when using IntelliJ/PyCharm remote debugging. Importing `pydevd_pycharm` at
+# the breakpoint will cause dep inference to add this dep on the remote debugger client.
+python_requirement_library(
+  name = "pydevd-pycharm",
+  requirements=["pydevd-pycharm==203.5419.8"],
+)

build-support/bin/ci.py

@@ -307,7 +307,7 @@ def run_check(command: List[str]) -> None:
 
 
 def run_lint(*, oauth_token_path: Optional[str] = None) -> None:
-    targets = ["build-support::", "examples::", "src::", "tests::"]
+    targets = ["build-support::", "src::", "tests::"]
     command = ["./pants.pex", "--tag=-nolint", "lint", "typecheck", *targets]
     if oauth_token_path:
         command.extend(_use_remote_execution(oauth_token_path))