feat(indexer-selection): make indexer-selection generic over candidae metadata

[LNSD]

Make the indexer-selection::Candidate type generic over candidate metadata, i.e., indexing ID and the indexing metadata (URL, largest allocation address, TAP support, etc.).

[Theodus]

I like the idea of removing dependencies by making a generic metadata field. But it seems incorrect to only use the indexer address for the ID, since that would it make it impossible to distinguish candidates across subgraph versions.

[LNSD]

I like the idea of removing dependencies by making a generic metadata field. But it seems incorrect to only use the indexer address for the ID, since that would it make it impossible to distinguish candidates across subgraph versions.

The idea will be to use the IndexerId type (which includes both) as the id field type.

[Theodus]

Sorry. I misunderstood part of the changes