Fix Low Capacity of Paging Tokens

[alexanderkiel]

POST-based FHIR searches use tokens in next links to hide the search parameters because they can contain sensitive data. That tokens are stored for 24 hours in an in-memory cache in the standalone storage mode. However that cache also had a fix limit of 10 MiB. That limit together with a wrong size calculation results in a rather low capacity of about 15,000 tokens. On top of that, with the introduction of first links (#961), links will also be generated on empty results. Real world generated searches using Flare showed that the capacity of the token cache can be exhausted quickly.

We will do the following:

• increase the memory limit to 100 MiB (Increase Local Page Store Size #1023)
• remove the first link from empty search results (Increase Local Page Store Size #1023)
• fix the size calculation of the tokens (Fix Weight Calculation in Page Store #1022)