Performance enhancements for DB v6 writes

[wagoodman]

All changes on this PR are purely to decrease the time it takes to build a v6 DB, which when incorporated the build time in CI drops from ~2.5 hours to ~25 minutes 🎉 (still characterizing, I'll report back with final times when this is out of draft)

Changes:

• add in-memory ID lookup for common or expensive models (e.g. CPEs originally had a large where clause to fetch similar rows, now this is an O(1) map lookup based on a string). This has been applied to CPEs, OperatingSystems, VulnerabilityHandles, and Providers. These are relatively flat records and based on debug logs appear to have a high cache hit rate. This also required ensuring we are correctly using this cache across transactions as well as within a transaction (deduplicating in memory).
• Minimizing use of any queries to the DB within BeforeCreate hooks
• keep blob digests in memory, not to a separate digests table (theme: maximize the items not written to the DB).
• organizes the store functions to be clear when shared transactions can be used internally vs separate transactions when using public functions.
• removed the pragma for 16KB page sizes (this had little effect on DB size and a small performance boost for write times).

While working on this, I did make some unrelated changes:

• I noticed that pragma statements are not strongly verified by sqlite, so explicit checks were added (when adding a new pragma).