fix: pattern based compression

[erights]

When the only specimens you store are those that match a pattern, store only the information which is not literally the same as the pattern.

Added to the store module

• compress(specimen, pattern) - returns bindings array, or undefined to indicate match failure
• mustCompress(specimen, pattern, label) - indicates failure with diagnostic including label
• decompress(bindings, pattern) - undoes the others.

Modified SwingSet's virtual mapStores so that if they have a valueShape option, they also use it for compression.

Modified ERTP's paymentLedger to provide the amountShape as the valueShape option for the durable ledger mapStore.

Verified in the debugger that we now only store a singleton array around the value itself, dropping the enclosing amount structure and the brand which is always the same for a given ledger mapStore. IOW, instead of storing the serialization of

{
   brand: moolaBrand,
   value: 2n,
}

for every live payment, with this PR we store the serialization of

[2n]

for every live payment. This is not just a savings because it is smaller. We also avoid needing to adjust the refcount of their common moolaBrand.

Once we've switched to smallcaps, the serialization of [2n] is tiny.

[erights]

Ready for review!

[erights]

Question for @FUDCo (Nevermind. Resolved)

[erights]

Closing in favor of #6432