Investigate use of search index library

[lidel]

(placeholder)

Parts of what ipfs-geoip does could be generalized and extracted into standalone search index generator / consumer libraries useful in other places (eg. wikipedia text search etc).
Or we could refactor it to use something that already exists.

Some prior art:

• https://0fps.net/2020/12/19/peer-to-peer-ordered-search-indexes/
• https://github.com/mikeal/chunky-trees