GLP flaky integration

[cruzdanilo]

for the GLP vaults, the underlying tokens should be transferred through the sGLP (staked). documentation here: https://gmxio.gitbook.io/gmx/contracts#transferring-staked-glp

the api is returning sGLP's address as the tokenAddress, so the front-end knows which token to transfer, but this has some side-effects. some integrations rely on tokenAddress to display underlying information about positions, and those integrations expect GLP as the underlying. this breaks GLP vaults on zapper, for example.

i think the api should return both addresses, and the front-end already calls this value locally as depositTokenAddress, so this could be a good field name here.