fix: log and exit on unhandled promise rejection

[bchrobot]

Description

Log the unhandled promise rejection and exit 1 on unhandled promise rejection.

Motivation and Context

This fixes the issue of pods not restarting on database connection errors. It will also provide
much better visibility into a variety of other unhandled promise rejections we get in Spoke.

Ref: nodejs/node#9523 (comment)

The current node warning suggests

To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict`

(see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode)

The added behavior will have the same effect.

How Has This Been Tested?

Locally:

1. brew services stop postgresql
2. git checkout master
3. yarn build:server
4. node --no-deprecation ./build/src/server
5. Observed that we get raw UnhandledPromiseRejectionWarning: Error: connect ECONNREFUSED 127.0.0.1:5432 log and node process remains alive
6. git checkout fix/log-and-exit-on-unhandled-rejection
7. yarn build:server
8. node --no-deprecation ./build/src/server
9. Observed that we get properly formatted error log and process exits

Screenshots (if appropriate):

N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Documentation Changes

N/A

Checklist:

• My code follows the code style of this project.
• My commit messages follow the Conventional Commits specification.
• My change requires a change to the documentation.
• I have included updates for the documentation accordingly.