Sequence v2: Faster local tracker and cache

[Agusx1211]

Improves performance of local instance of sequence-sessions:

• Add ram cache for imageHash -> config
• Add ram cache for payload
• Remove local ram cache for configs on loadPresignedConfiguration (no longer needed)
• Sort checkpoints before validating signatures (that way we can get faster to the best one)
• Skip encoding if no signatures are found for the payload
• Skip checkpoint check if main tracker and cache already match

There is room for improvement, loadPresignedConfiguration could avoid recursion (opening room for new optimizations) and IndexedDB can also use bulk operations (or we could copy everything into memory).