Seperate scanner helper table initialisation

[darrell-k]

@michaelherger , what do you think?

[michaelherger]

What would be the benefit of this change?

[darrell-k]

Prevents schema_scanner.sql being run multiple times at the beginning of the scanner process. When the call is in migrateDB, it runs 3 times in a n&c: initially, then when FTS SQL functions are registered and when the new SQL functions we discussed earlier are registered; and 4 times in a full rescan (additionally from wipeDB).

[michaelherger]

The same applies to the schema migration, doesn't it? It's still wasteful there. Is it worth the change? Oh well, simple enough.

[michaelherger]

Oh, I can't merge - this is all your repository 😁.

[darrell-k]

I'll merge it, then it will appear in LMS-Community#1637

I don't think the rest of migrateDB does anything unless a schema change is detected.