refactor: Only load federation clients when gateway boots

[m1sterc001guy]

See #3781 (comment) for context.

• Removes DatabaseSource
• Adds check when connecting a federation if the federation has already been connected
• Wraps every usage of lnrpc behind a wrapper function that first checks if the lightning node is connected to the gateway.

[codecov]

Codecov Report

Attention: 48 lines in your changes are missing coverage. Please review.

Comparison is base (9c36777) 58.28% compared to head (e52d9ee) 58.38%.

Files	Patch %	Lines
gateway/ln-gateway/src/lib.rs	65.59%	32 Missing ⚠️
gateway/ln-gateway/src/state_machine/pay.rs	85.71%	6 Missing ⚠️
gateway/ln-gateway/src/state_machine/complete.rs	85.18%	4 Missing ⚠️
fedimint-cli/src/lib.rs	0.00%	1 Missing ⚠️
fedimint-client/src/lib.rs	87.50%	1 Missing ⚠️
fedimint-load-test-tool/src/common.rs	0.00%	1 Missing ⚠️
fedimint-wasm-tests/src/lib.rs	0.00%	1 Missing ⚠️
gateway/ln-gateway/src/client.rs	90.90%	1 Missing ⚠️
gateway/ln-gateway/src/state_machine/mod.rs	91.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4026      +/-   ##
==========================================
+ Coverage   58.28%   58.38%   +0.09%     
==========================================
  Files         193      193              
  Lines       42580    42552      -28     
==========================================
+ Hits        24819    24842      +23     
+ Misses      17761    17710      -51     

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[dpc]

LGTM, but someone that understands lngateway should look.

[okjodom]

reviewed and tested 1588620 looks good to me

[douglaz]

LGTM