Re-add linter, get standardrb to pass again

[h-m-m]

Summary

We want to use a linter to help minimize surprises when submitting PRs and reviewing them

Things to Consider

@abachman started a PR, #168, that looks like what we want, but our branching/merging churn was very heavy at the time so he decided to postpone

His follow-up, #170, shows where in the pipeline you need to remove comments to enable linting again

Criteria for Completion

• A linter that checks for standardrb compliance runs
• The linter will flunk non-standard code
• The linter adds a green check to PRs that pass the standard
• The PR enabling the linter passes the standard

[Naraveni]

can I work on this

[h-m-m]

@Naraveni Go for it! I look forward to seeing your PR