Import cosmos-sdk coin types

[gsora]

This PR imports Coin, DecCoin and their slice versions into this repository so we can use the code with no dependency on Cosmos SDK, so we can drop most of the SDK dependencies when coin parsing is needed.

[gsora]

Thoughts on this @sahith-narahari @sgerogia @DeshErBojhaa?

[sahith-narahari]

So we're forking the coins type of sdk and maintaining it here in utils?

[gsora]

I wouldn't call it a full-blown fork, rather we're "importing" those types in our codebase. We're not planning to modify them in any meaningful way, just keep them here to avoid linking the whole SDK for simple Coin parsing.

[DeshErBojhaa]

Hi, if the code does not change, then I think it's a viable approach.
A couple of questions though:

1. How likely that the upstream will remain the same? By upstream, I mean, say for Coin how likely it will remain unchanged, i.e. no new attributes added/updated? Coin type is just an example, I hope you get the idea.
2. Why we're not doing the same with util packages? Each repo will have its own util package and customize it as it deems necessary.

[gsora]

How likely that the upstream will remain the same? By upstream, I mean, say for Coin how likely it will remain unchanged, i.e. no new attributes added/updated? Coin type is just an example, I hope you get the idea.

Highly unlikely, considering Coin is the smallest unit available in Cosmos SDK - it can happen but IMO not in the short-mid term (1-5 years).

Why we're not doing the same with util packages? Each repo will have its own util package and customize it as it deems necessary.

Not sure I got your question.

[sahith-narahari]

2. Why we're not doing the same with util packages? Each repo will have its own util package and customize it as it deems necessary.

I don't think each repo needs it's own utils, they'll be very similar so it makes more sense to have one utils. Hope I got your question right

[DeshErBojhaa]

Not sure I got your question.

@sahith-narahari answered it. :)