feat: entry page retrieval

[harrysolovay]

Resolves #643

Allows one to retrieve a list of entries as they do a list of keys.

import { Uniques } from "statemint/mod.ts"

const collections = Uniques.Class.entryPage(100)

const result = await collections.run()

console.log(result)

Will soon be complemented by #567.

Note: was confused by the name of the result, storage changeset. Doesn't represent a diff after all.

[tjjfvi]

state_queryStorageAt isn't the right method. Looks like we'll either need to use mapArray or give up paging and use state_getPairs.

Note: was confused by the name of the result, storage changeset. Doesn't represent a diff after all.

The first entry doesn't, but subsequent entries do.

[harrysolovay]

This is the same approach used by pjs apps.

Try reading statemine's uniques classes storage map. Same output.

getPairs is deprecated and calling it results in a server error.

This approach allows for retrieval with 2 round trips... that being said, yea: it's not the prettiest. Not sure if we have any better alternative though.

[harrysolovay]

The first entry doesn't, but subsequent entries do.

This is interesting. Yea, even if we did go this route, we'd need to skip decoding the subsequent diffs.

[tjjfvi]

Ah, I confused state_queryStorageAt with state_queryStorage. The former does a single block, the latter is the history-diffing one.

Eventually we should rename .entry to .get or .value, but for now I think we should leave it as-is.