Improve dictionaries, sets, tuples, lists for all backends

[certik]

We have initial implementation working, we now have to extend it to work for all backends well, support printing, etc.

[faze-geek]

Also some improvements regarding Data Structures which @kabra1110 and I discussed recently -

1. Support for general nesting - Consider nested dictionaries or something more complex like dict of set of list of tuple. It is interesting to explore if something like this can be supported keeping in mind that LPython is statically typed.
2. Usage of data structures within functions.
3. Derived data structures from cpp which are supported in Cpython - stack, queue, heap(priority_queue), trie.