FX - support dynamic fees24 in snapshots

[gmbronco]

context: #1101

Don't we also need to update how the fees24h is computed in pool.snapshot-service.ts? (note: this file seems to exist in two places)

The code assumes a static pool swap fee, but FX pools have a dynamic swap fee

fees24h: volume24h * parseFloat(poolAtBlock.swapFee)
I'm thinking something like this might work:

fees24h: parseFloat(pool.totalSwapFee) - parseFloat(pool24hAgo.totalSwapFee)