Update child emulator and improve manifest dataset download

[cortadocodes]

Contents (#668)

IMPORTANT: There are 2 breaking changes.

Enhancements

• 💥 BREAKING CHANGE: Update ChildEmulator to use EventReplayer, support schema-compliant events and attributes, and support heartbeats and delivery acknowledgement events. This significantly simplifies the emulator
• 💥 BREAKING CHANGE: Remove ChildEmulator.from_file
• Download manifest datasets to same directory by default

Refactoring

• Move ServicePatcher into its own module

---

Upgrade instructions

💥 Update `ChildEmulator` to use `EventReplayer` and full events

Give events (including attributes) that satisfy the service communication schema to child emulators.

💥 Remove `ChildEmulator.from_file`

Load the JSON file separately and pass the events into the ChildEmulator constructor.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 96.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 94.55%. Comparing base (330ea82) to head (ed77f40).
Report is 243 commits behind head on main.

Files	Patch %	Lines
octue/cloud/emulators/child.py	92.30%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #668      +/-   ##
==========================================
- Coverage   94.62%   94.55%   -0.07%     
==========================================
  Files          82       83       +1     
  Lines        3552     3546       -6     
==========================================
- Hits         3361     3353       -8     
- Misses        191      193       +2     

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