Fix line numbers for new annotation linting

See https://github.com/edx/edx-lint/blob/master/CHANGELOG.rst#302---2021-01-26

Add constraints.txt file

See https://github.com/edx/edx-lint/blob/master/CHANGELOG.rst#301---2021-01-26

Add setting and toggle annotation linting

See https://github.com/edx/edx-lint/blob/master/CHANGELOG.rst#300---2021-01-24

Adding global constraint file.

A central location for most common version constraints (across edx repos) for pip-installation.

Adding global constraint file.

A central location for most common version constraints (across edx repos) for pip-installation.

v1.5.0

• Breaking: dropped support for Python 2.
• Pylintrc: dropped code scoring.
• Fixed: the .editorconfig file was not installed, and so was not writable.
• Added support for Python 3.8

Upgrade pylint

Upgrades to latest pylint that supports Python 2.

Add Feature Toggle Linter

Adds a linter to find feature toggles that are missing documentation, as well as waffle methods that are now illegal.

FIX: Remove ungrouped-imports from pylint

It wasn't enough to remove ungrouped-imports from the enabled list, it needed to be added to the disabled list.

Remove ungrouped-imports from pylint

Pylint will no longer complain about ungrouped-imports. This rule was incompatible
with the isort rules that group import x together before from x import y, which
would sometimes separate rules for the same repo.