Ensure reasonable size of Omnipool position

[mrq1911]

to avoid spam and dust on the chain we should check that you cannot create or update omnipool position so its value is lower than some boud (for example 1000 HDX)

[jak-pan]

This is also problematic with LM on top.

[jak-pan]

I think there are 2 issues intertwined.

1. Storage - We could just charge more for NFT creation and then possibly refund?
2. Nonsensical computation + LM problems.

We need to make sure that this is not exploitable. If we add deposit for position, we need to make sure the deposit either stays in account locked or is recorded in position or not change the price.

If we add minimal limit it shouldn't change and should be per-asset otherwise you might lock yourself out as we had this problem in the past in XYK.