Use locally built bramble in docker setup

[lucianjon]

I wanted to test out some changes I was making and realised our docker-compose setup only uses already published bramble images. Given this is the quickest way to a working setup I figured it's more useful to build the docker image locally.

Changes

• Changed the main bramble Dockerfile to instead be a self-contained multi-stage docker build, in order to make it easier to work with docker-compose.
• Moved the docker-compose file from examples to the root.
• Updated the github actions to work with the new multi-stage docker build.
• Also migrated the actions to their latest versions.
• Added health checks to each example service so bramble doesn't start before them and immediately exit.
• Ended up having to mess with the linter action as it wasn't happy with my changes.

[codecov-commenter]

Codecov Report

Merging #140 (149b254) into main (e365c96) will increase coverage by 0.03%. The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #140      +/-   ##
==========================================
+ Coverage   69.58%   69.61%   +0.03%     
==========================================
  Files          24       24              
  Lines        2630     2630              
==========================================
+ Hits         1830     1831       +1     
+ Misses        669      668       -1     
  Partials      131      131              

Impacted Files	Coverage Δ
auth.go	87.42% <0.00%> (+0.62%)	:arrow_up:

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