feat: add mendi adapter

[gathonwar]

fix: zero values and math rounding

[0xroll]

hi @gathonwar

some questions on this PR :

1. is this returning the net balance? net asset balance = supplied - borrowed
2. this doesnt seem to factor in interests gained/accrued from supplying and borrowing

kindly provide the subgraph repo link

[nitish-91]

@gathonwar can you please implement the function as mentioned in the readme.
https://github.com/delta-hq/l2-lxp-liquidity-reward/tree/main?tab=readme-ov-file#code-changes-expected

Also please reply to @0xroll 's questions

[gathonwar]

hi @0xroll,

1. yes, these are net balances
2. interest are accumulated in supply side because we are using tokens and exchange rate to calculate supplied amount. they were not included in borrow side, the second commit is getting borrow balance at block number (interests are included).