Signaling server rewrite

[ValorZard]

Description

The current way the signaling server works annoys me, so I'm going to do my best to rewrite it

Reference issue

Part of https://github.com/pion/example-webrtc-applications/issues/372

[codecov[bot]]

Codecov Report

:x: Patch coverage is 0% with 39 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 0.00%. Comparing base (87d915d) to head (7349f4f). :warning: Report is 7 commits behind head on master.

Files with missing lines	Patch %	Lines
ebiten-game/game/main.go	0.00%	19 Missing :warning:
ebiten-game/signaling-server/main.go	0.00%	19 Missing :warning:
ebiten-game/game/ui.go	0.00%	1 Missing :warning:

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #373     +/-   ##
========================================
  Coverage    0.00%   0.00%             
========================================
  Files          28      11     -17     
  Lines        3633     931   -2702     
========================================
+ Misses       3633     931   -2702     

Flag	Coverage Δ
go	?
wasm	0.00% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

:rocket: New features to boost your workflow:

• :snowflake: Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• :package: JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[ValorZard]

(For any interested onlookers - I probably won't be coming back to this PR for the forseeable future, so feel free to take up the challenge if you're interested)