Fix unit test package scripts

[rekmarks]

This PR fixes our local unit test package scripts. When the state migration unit tests were migrated to Jest in #12106, it left the test:unit script in a broken state, because it didn't tell mocha to ignore the state migration tests.

Arguably, that script was already broken, since the most reasonably expectation from its name is that it runs all unit tests. The PR makes it so that it does just that, by means of concurrently.

Unfortunately, concurrently only outputs errors from child processes once (at the time when they exit, open-cli-tools/concurrently#134). This means that we have to search/navigate the output for this combined script to identify the failure. That said, it's better than the status quo.

[metamaskbot]

Builds ready [ae0ea77]

• builds: chrome, firefox, opera
• build viz: Build System
• code coverage: Report
• storybook: Storybook
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4, 5, 6, 7, 8
  • common: 0, 1, 2, 3
  • content-script: 0
  • contentscript: contentscript
  • disable-console: disable-console
  • inpage: inpage
  • phishing-detect: phishing-detect
  • sentry-install: sentry-install
  • ui: 0, 1, 2, 3, 4, 5

Page Load Metrics (297 ± 28 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	61	420	247	89	43
		domContentLoaded	233	410	281	58	28
		load	250	440	297	58	28
		domInteractive	233	410	281	58	28

[jpuri]

Nice change 👍