fix: Vela-Exchange new endpoints + small refacto

[0xpeluche]

Fix for the Vela-Exchange update, it seems that the endpoints have changed -> new GraphQL endpoint implemented + small refacto since staking_base_ staking_arbitrum_ were similar function

[llamatester]

The adapter at projects/vela-exchange exports TVL:

arbitrum                  6.39 M
staking                   1.21 M
arbitrum-staking          1.20 M
base                      74.25 k
base-staking              14.79 k

total                    6.47 M 

[g1nt0ki]

looks good