Consider building Flowfuse container image as a part of `FlowFuse/flowfuse`

This task aims to collect opinions about the idea. Prpper tasks should be created once decision is made.

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At this moment the flow for building flowfuse app used by the FFC is:

1. Update the code within `FlowFuse/flowfuse` repo
2. Build the npm package (`nightly`)
3. Trigger container build in `FlowFuse/helm` repo
4. Update container image and trigger FFC deployment workflow in `FlowFuse/CloudProject`

Running container image build as a part of `FlowFuse/flowfuse` will:
* shorten the delivery time
* simplifies FFC deployment tracking
* decrease the management burden

Also, keeping contianer image build next to the application code is a common approach.

Same approach could be made to fileServer container image.