Configure dev container

[jazairi]

Why these changes are being introduced:

Dev containers make it easier to develop apps
without maintaining a local Ruby/Rails
environment.

Relevant ticket(s):

• TCO-89

How this addresses that need:

This adds dev container config files and
documentation.

Side effects of this change:

Gemfile.lock now includes aarch64-linux, probably
because I ran the dev container on my Macbook.

Developer

Accessibility

• ANDI or WAVE has been run in accordance to our guide.
• This PR contains no changes to the view layer.
• New issues flagged by ANDI or WAVE have been resolved.
• New issues flagged by ANDI or WAVE have been ticketed (link in the Pull Request details above).
• No new accessibility issues have been flagged.

New ENV

• All new ENV is documented in README.
• All new ENV has been added to Heroku Pipeline, Staging and Prod.
• ENV has not changed.

Approval beyond code review

• UXWS/stakeholder approval has been confirmed.
• UXWS/stakeholder review will be completed retroactively.
• UXWS/stakeholder review is not needed.

Additional context needed to review

To confirm the dev container works, open the repo in VS Code. You should see a prompt to open the dev container. From there, in a terminal, commands like ruby -v and rails -v should return the expected values, rails s should start a server, and rails t should run the test suite.

Code Reviewer

Code

• I have confirmed that the code works as intended.
• Any CodeClimate issues have been fixed or confirmed as
  added technical debt.

Documentation

• The commit message is clear and follows our guidelines
  (not just this pull request message).
• The documentation has been updated or is unnecessary.
• New dependencies are appropriate or there were no changes.

Testing

• There are appropriate tests covering any new functionality.
• No additional test coverage is required.

[coveralls]

Pull Request Test Coverage Report for Build 17446106187

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.2%) to 98.49%

---

Files with Coverage Reduction	New Missed Lines	%
app/controllers/search_controller.rb	1	98.11%

Totals
Change from base Build 16027462749:	-0.2%
Covered Lines:	587
Relevant Lines:	596

---

💛 - Coveralls