Bug 32799: Rename ILLSTATUS authorised value category to ILL_STATUS_ALIAS

Bug 32799: Rename ILLSTATUS authorised value category to ILL_STATUS_ALIAS

To test:
1) Activate the IllModule system preference
2) Install a backend (BLDSS or FreeForm) following the wiki instructions:
3) Configure some authorised values for ILLSTATUS
4) Apply patch
5) Run database update
6) Verify your configured values have been updated to ILL_STATUS_ALIAS
7) Add another ILL_STATUS_ALIAS: there should now be an explanation in the
   categories list
8) Go to the ILL module and add a new request
9) Edit the request, verify that your status alias show in the status list
10) Set one of your status and save
11) Verify that the ILL requests list search filters show your status alias
12) Manage the request again and verify that the ILL request log shows the
    status descriptions correctly
13) Verify the description of the ILLHiddenRequestStatuses has
    been updated with the new authorised value category

Signed-off-by: Pedro Amorim <pedro.amorim@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>