[Python] Replace global linting excludes with local line-level excludes ("noqa")

Replace the project global linting rule excludes (as defined in .pep8) with
fine-grained "# noqa" annotations.

By using noqa annotation the excludes are made on a per line basis instead of
globally.

These annotations are used where we make deliberate deviations from the standard
linting rules.

To lint the Python code in the project:

  $ flake8

To install flake8:

  $ pip install flake8

See https://flake8.readthedocs.org/en/latest/ for details.

To enable checking of the PEP-8 naming conventions, install the optional
extension pep8-naming:

  $ pip install pep8-naming

To enable checking of blind "except:" statements, install the optional
extension flake8-blind-except:

  $ pip install flake8-blind-except

To enable checking of import statement order, install the optional
extension flake8-import-order:

  $ pip install flake8-import-order

utils/pass-pipeline/scripts/pipelines_build_script.py

@@ -10,7 +10,7 @@ import textwrap
 sys.path.append(os.path.join(os.path.dirname(
     os.path.dirname(os.path.abspath(__file__))), 'src'))
 
-import passes
+import passes  # noqa (E402 module level import not at top of file)
 
 # TODO: This should not be hard coded.
 PIPELINES = ["PreSpecialize", "HighLevel", "EarlyLoopOpt",