Store fixtures in redis with indexes

[gantoine]

This PR starts storing the in-code and network-fetched fixtures in Redis with hashed keys for quick access. The benefits of this change are:

• One-time loading of static fixtures into cache (faster restarts)
• No need to read fixtures into memory on each scan
• Fixtures persist between container removals
• Nightly background task pulls fresh json and updates fixtures
• Can run the container as non-root user

Also changed:

• Store MAME fixture as json file
• Mark /romm/config as a required volume (even empty)
• Update emulatorjs to 4.0.12
• Fix crash when scanning new platforms only
• Remove the task that updates the MAME fixture
• Add fakeredis to initialize a client for testing
• Added icons for turbografx-16

[github-actions]

Test Results

73 tests  ±0   73 ✅ ±0   22s ⏱️ +2s
 1 suites ±0    0 💤 ±0 
 1 files   ±0    0 ❌ ±0 

Results for commit a81b14d. ± Comparison against base commit 1f09eb4.

♻️ This comment has been updated with latest results.