Add functionality for nested tags

[VijayrajS]

Summary

Backend changes corresponding to InetIntel/grip-ui#25 - Nesting of tags is being done for event and pfx_event endpoints in order for the frontend to consume and display details for the same with ease.

As discussed, the groupings should be on irr-[IRR]-[common_suffix] families of tags, where:

• IRR can be multiple different (not necessarily all of them) IRR names belonging to this list: [ARIN, RADB, BELL, BBOI, LACNIC, LEVEL3, NTTCOM, TC, WCGDB, AFRINIC, ALTDB, APNIC, ARIN, CANARIE, IDNIC, PANIX, REACH, RIPE, RIPE-NONAUTH, OPENFACE, JPIRR, NESTEGG].
• common_suffix must be the same for all tags in the same family/group and can be one of the: [all-newcomer-exact-record, all-newcomer-more-specific-record, all-newcomer-no-record, some-newcomer-exact-record, some-newcomer-more-specific-record, some-newcomer-no-record, all-oldcomer-exact-record, all-oldcomer-more-specific-record, all-oldcomer-no-record, some-oldcomer-exact-record, some-oldcomer-more-specific-record, some-oldcomer-no-record]

The GET calls for these endpoints have a version endpoint. If set to 'v2', we get the new, modified responses which would look like:

{
    "all-newcomer-exact-record": [
        "irr-ARIN-all-newcomer-exact-record",
        "irr-RADB-all-newcomer-exact-record",
        ...
    ],
    "all-newcomer-no-record": [...],
    ...
   "other": [list of other tags that don't follow the irr-[IRR_name/all]-[suffix] format]
}

Additionally, the /tags endpoint will have an additional key called nested_tag_descriptions, which will have descriptions for the parent tag (to display on the parent tag tooltips).

Testing

API testing pending.

Issues

InetIntel/grip-ui#25