Limit resources for basemap generation & replace go binaries with external microservice

[spwoodcock]

Is your feature request related to a problem? Please describe.

• Follow on from Fix TMS issues by using go-tilepacks and go-pmtiles #2162
• There are no resource restrictions on the basemap generation.
• Generating basemaps can lock up the FastAPI server until complete.

Describe the solution you'd like

• Optimise number of workers for tilepack binary (a command line flag).
• In the long run integrate https://github.com/hotosm/basemap-api instead of running the binaries directly in the FastAPI container.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context

• This shouldn't be as much of an issue on servers with multiple API replicas and resource constraints.
• fmtm.hotosm.org prod is deployed with 4 replicas, 1.5GB RAM each, so should be fine for now.
• To use this type of setup, use the compose.main.yaml file, plus tweak the API_REPLICAS as needed (default 4).