[Parent] Prototype the new indexing system

[hannahhoward]

Building on storacha/RFC#29, we are now ready to prototype various components of the new indexing system.

IPNI

• Spec the metadata for IPNI advertisement chains for Location Claims and for Sharded Dag Indexes #103
• Implement the location claim IPNI advertisement chain (for now, just on our node) indexing-service#2
• Implement the sharded dag index IPNI advertisement chain indexing-service#3

W3UP Index Cache

• Define the internal data model for the W3UP Index Cache #106
• Suggest a datastore for W3 Index Cache #108
• Prototype the W3 Index cache #107
• Write through operations for the W3UP Index Cache #109
• Read through operations for the W3UP Index Cache #110

W3UP Index

• Define an HTTP interface for the indexing service based on the Service class, that generally mirrors content claims indexing-service#4