Migrate from superLinter to megalinter

This project is still using superlinter, which pulls a large image file, runs slowly, and is difficult to maintain in a development environment as well as parse errors in its log result. We since have switched to megalinter in our project template and other projects, we should make a similar migration here for more efficient testing and linting. On implementation, should largely follow the process outlined in the project template, https://github.com/azavea/azavea-project-template/pull/50.

Start by reviewing the current superLinter configuration in the repository and the migration process in azavea-project-template PR 50. Replace the existing linter setup with megalinter, then confirm that the project’s linting runs successfully and produces parseable errors.

Written by the indexing model from the issue text.