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ARROW-6649: [R] print methods for Array, ChunkedArray, Table, RecordBatch

See the readme and the new tests for example output.

This patch also fixes a validation bug in `dictionary()`, aliases that to `DictionaryType$create`, and adds default arguments.

Closes #5492 from nealrichardson/print-methods and squashes the following commits:

c092d3071 <Neal Richardson> Merge branch 'print-methods' of github.com:nealrichardson/arrow into print-methods
02afb89f2 <Neal Richardson> Prettier printing of dictionary type's ordered attribute
57501004a <Neal Richardson> indices in the docs too
6be0328d2 <Neal Richardson> indices
2d4e744bd <Neal Richardson> Add/improve print methods for Array, ChunkedArray, Table, RecordBatch

Authored-by: Neal Richardson <neal.p.richardson@gmail.com>
Signed-off-by: Neal Richardson <neal.p.richardson@gmail.com>