feat: vault tvl history

[murderteeth]

Seafood is currently fetching 3-week TVL history for every vault on each network by posting promql to https://yearn.vision/api/ds/query. This has been OK, but may prove fragile long term (eg because of feature\design drift on the exporter side, promql is a relatively uncommon skill, etc).

Can TVL history be added to the high level api? Suggesting something like this:

/tvl/[network]/vaults?frequency=weekly&periods=3

Fwiw, here's the promql seafood uses, https://github.com/yearn/seafood/blob/main/api/routes/vision/tvls.json