init code hell

[treeder]

This took a long time to figure out, but the init_code for Pair's is hardcoded into router and has to change everytime the factory changes, solidity version changes, or whatever else.

Could have router call this function directly from Factory to get the init_code and use it when generating a pair address: goswap/uniswap-v2-core@2a80c52#diff-baf33e06a441bb84df3d784b143aac5eR50