Initial implementation

• remove kedifa-csr, as users of KeDiFa shall for now take care about certificates by themselves (see https://lab.nexedi.com/nexedi/slapos/merge_requests/434#note_69248 and https://lab.nexedi.com/nexedi/slapos/merge_requests/434#note_69359 )
• implement ID reservation as described in https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_69235 with possible updates
• implement real submission_date of a certificate
  • https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68679
  • just check not_valid_before and not_valid_after dates
  • order by submission_date not not_valid_before
  • fix wording https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68666
• https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68667
• https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68668
• Improve reloading process, and update CA and CRL in app, as it is done on SSL layer (https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68921)
• https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68670
• improve licensing https://lab.nexedi.com/luke/kedifa/commit/9a55bb020b69860e21917ecc7d36c6550edb741b#note_68808
• https://lab.nexedi.com/luke/kedifa/commit/f6584b43f8718734e55e6f8284634c59bf938b96#note_68851
• document proper content type application/x-x509-ca-cert on PUT verb (see https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_69042)
• try to provide nice Location after putting certificate https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68680
• improve key encoding https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68644
• Use Organisational Unit instead of Common Name https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68640
• use _executeSingleRow instead of unneeded complication https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68654
• use the fact that Cursor is iterator https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68658
• raise instead of returning https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68674
• test and defend against invalid QUERY_STRING https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68676
• check CRLs in app instead of ssl_context https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68689
• keep DELETE queries in one gc-like method https://lab.nexedi.com/luke/kedifa/merge_requests/1#note_68659
• implement missing tests
• convert not implemented and agreed discussions to TODO in the repo