Refactor: Change Pool API to have separate methods for JoinPool and JoinPoolNoSwap

[ValarDragon]

Background

Currently we have a single JoinPool and CalcJoinPoolShares method on the pool API. Something thats become quite clear in #2126 , is that this is terrible for client side users right now, and we need to split the AMM interface to have JoinPool and JoinPoolNoSwap OR make JoinPool just implement the no swap side.

I'm in preference of separating the go API, seeing as we already separate the proto API for messages.

At the moment, theres no clean way to estimate the JoinPoolNoSwap share amount out. IDK what the CLI does here, and I think theres no real way for other users to get the right numbers on multi-asset joins.

Suggested Design

• Make a new JoinPoolNoSwap and CalcJoinPoolNoSwapShares methods on pool interface
• Delete the code we had to introduce into simulator logic to emulate this https://github.com/osmosis-labs/osmosis/pull/2091/files#diff-77253003f1d97ce0424f8d9a21f789b506c6e01c20f89ef0220dfd6d61fc5e95R57-R96
• Make state machine call this for JoinPoolNoSwap
• Make JoinPool code have code re-use with this
• Adjust tests

Acceptance Criteria

• We've improved the JoinPoolNoSwap API so that we can in golang easily estimate it, and delete that function in the simulator.