Bug 34387: Improve API docs naming consistency

Bug 34387: Improve API docs naming consistency

This patch aims to make our API docs be more consistent.
It addresses two particular things:

* There's no consistency on the `tags` used across the spec, and not all
  of them are correctly described and have an `x-displayName` entry.
  More on this later.
* This are not sorted either by some for of grouping, or at least
  alphabetically.

For the former, I did my best trying to harmonize (specially on the ERM
front) with what we do in the rest of the use cases.

For the latter, I opted for sorting everything alphabetically, as a
first step. Hoping someone else could work on grouping things.

To test (ON YOUR HOST MACHINE):
1. On current master run:
   $ cd api/v1/swagger
   $ docker run --rm -v $(pwd):/api --workdir /api redocly/cli \
           build-docs swagger.yaml --output index.html
=> SUCCESS: It doesn't break or anything
2. Open your browser, open the generated api/v1/swagger/index.html file
=> FAIL: The left column has
         * several lower case entries
         * not everything is correctly grouped (ERM? packages?)
         * Things are not sorted. There's an attempt but looks messy
3. Apply this patch
4. Repeat 1 and 2
=> SUCCESS: Things look much better!
5. Sign off :-D

CAVEAT1: I'm not sure why, but import_batches doesn't work. Ideas are
welcome, I'll keep looking for fixes.
CAVEAT2: I don't have enough eHoldings background to weight in, but I
feel like 'ERM eHoldings packages' could just be 'ERM packages'.
Follw-up patches with better ideas are welcome.
CAVEAT3: Patron credits, debits, balance... They could all go in to
'Patrons accounts' or similar. Open to ideas.
CAVEAT4: Old redocly didn't support mapping an endpoint to more than one
target section. Something to explore if we want (for example) to reach
'credits' through the 'Patrons' section but also from 'Accounting'.

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>