Support new tag iso8583 in addition to index

[alovak]

Using tag index was not a good idea, typically, tags named as json, xml, sql. In the context of this package, it should be named iso8583. Also, when we add more attributes to the tag like "3,keepzero", the name index does not make any sense.

We should support the following: Amount int iso8583:"3,keepzero"and keepindex` for compatibility.

POC for this is implemented here: https://github.com/moov-io/iso8583/pull/273/files

[GalihFajar]

hi @alovak I'd like to work on this issue (I'm currently delving into the repository so can't promise much 🙇 ).

[alovak]

@GalihFajar afaik @mfdeveloper508 is working on this issue. You can look at this issue: #292. It doesn't require many changes, and it seems like a good choice for the first issue.

[GalihFajar]

Thanks @alovak, will look onto that one

[alovak]

closed in #293