Implement new `apify-client-js` methods in Crawlee storages

[barjin]

Since in SDK we want to switch from custom implementation of getPublicUrl to calling the client implementations of those methods (see apify/apify-sdk-js#433), we should add those methods to the local storage implementations in Crawlee as well.

The following methods are missing from the memory-storage in Crawlee (and are supported in apify-client-js):

For KVS:

+ createKeysPublicUrl
+ getRecordPublicUrl

For Dataset:

+ createItemsPublicUrl
+ getStatistics

[B4nan]

I think we can close this, it's superseded by the v4 storage rework (#3075) and apify/apify-sdk-js#643:

• getRecordPublicUrl: the v4 KeyValueStoreBackend interface has getPublicUrl(), local backends implement it, and the SDK backend delegates to the client's getRecordPublicUrl (including URL signing).
• createKeysPublicUrl/createItemsPublicUrl/getStatistics are platform-only features with no local-storage semantics, so they don't fit the v4 backend interface. If we want them as first class API, that belongs to the SDK storage classes (new issue).

apify/apify-sdk-js#433 stays open for the getPublicUrl deprecation/rename part.

[barjin]

I agree, closing as obsolete