Subgraph name should be unique with limit of 32 chars

[0xsarvesh]

subgraph name has restriction of 32 chars after / character. Current implementation does substring of contract address to fit in size(Refer link). This logic doesn't guarantee the uniqueness in subgraph name.

https://github.com/mosaicdao/mosaic-chains/blob/cc36441350dac99c5225d8e0cf9db25b90bdbedf/src/Graph/SubGraph.ts#L178

One of the approach is to use a hashing function which takes 40bytes contract address as input and returns 16 bytes hash which could be used for subgraph name.