Gitpod env files

[mattw-nws]

NOTE: based on #397, that should merge first.

Adds config files that allow a Gitpod workspace started from the ngen repo context to be preconfigured to successfully build, and builds ngen and all present submodules.

Additions

• .gitpod.Dockerfile Small dockerfile that prepares the packages necessary to compile build and run
• .gitpod.yml Set of tasks to build all of ngen

Removals

• None

Changes

• None*

Testing

1. All tests were run except parallel tests...this environment isn't yet set up to do parallel builds (may or may not be worth it). Routing test fails, but I don't think that passes anywhere right now.

Screenshots

Notes

• Based on GCC 11 fixes #397, which should merge first.

Todos

• Possibly also set up for parallel builds?

Checklist

• PR has an informative and human-readable title
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows project standards (link if applicable)
• Passes all existing automated tests
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future todos are captured in comments
• Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)
• Reviewers requested with the Reviewers tool ➡️

Testing checklist (automated report can be put here)

Target Environment support

• Linux