[Go]: Add IndexField and InsertField for Schema

[yevgenypats]

Describe the enhancement requested

Similar to the cpp and python library - https://arrow.apache.org/docs/python/generated/pyarrow.Schema.html#pyarrow.Schema

IndexField and InsertField can be quite useful.

Component(s)

Go

[singh1203]

@zeroshade, is addressing this issue required? If so, do you think I should take this up?

[zeroshade]

This was already added, there is an AddField method on arrow.Schema and FieldIndices