Add multicall getters

[gvladika]

Commit adds:

• provide l2MulticallTemplate in constructor. It is set as immutable and code hash is stored, so it can be used to calculate address of canonical L2 multicall. We do this in constructor because of contract size limits
• deploy L1 multicall by script when token bridge is created. Provide the address along with templates. We store L1 multicall address for client convenience

[gzeoneth]

lgtm, minor comments