bug#44976: 28.0.50; bibtex.el does not consider biblatex field name aliases

[leonard]

bibtex.el does not consider biblatex aliases correctly. The biblatex package
documentation specifies in Section 2.2.5 beginning on page 32 a series of
Field Aliases.

These include for example the alias "journal" for "journaltitle" which helps
biblatex to preserve backwards compatibility with bibtex. This causes bibtex.el
to throw error messages of the style "Mandatory field `%s' is missing" despite
the alias field being present.

To reproduce run `emacs -Q`. Then switch to `bibtex-mode` and set
`(bibtex-set-dialect 'biblatex t)`. Finally paste

  @article{doe2020lorem,
    author = {John Doe},
    title = {Lorem Ipsum},
    date = {2020},
    journal = {Communications of the ACM}
  }

and navigate the cursor into the @article entry. Then execute `M-x
bibtex-clean-entry` and observe "Mandatory field ‘journaltitle’ is missing"
error message.

In GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.20, cairo 
version 1.16.0)
 of 2020-11-30 built locally
Repository revision: 21104e6808a4496afb8163d92c6fb4d59e3010b7
Repository branch: feature/native-comp
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
System Description: Ubuntu 20.04.1 LTS

Configured using:
 'configure --with-cairo --with-modules --with-nativecomp'

Configured features:
XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND GPM DBUS GSETTINGS GLIB NOTIFY
INOTIFY ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE HARFBUZZ M17N_FLT LIBOTF
ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES NATIVE_COMP THREADS
LIBSYSTEMD PDUMPER LCMS2

Important settings:
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: BibTeX

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
rfc822 mml mml-sec epa derived epg epg-config gnus-util rmail
rmail-loaddefs auth-source eieio eieio-core eieio-loaddefs
password-cache json map text-property-search mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
comp comp-cstr warnings rx cl-seq cl-macs cl-extra seq byte-opt gv
bytecomp byte-compile cconv rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils help-fns radix-tree cl-print debug backtrace
help-mode find-func bibtex easymenu time-date subr-x cl-loaddefs cl-lib
tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode elisp-mode
lisp-mode prog-mode register page tab-bar menu-bar rfn-eshadow isearch
timer select scroll-bar mouse jit-lock font-lock syntax facemenu
font-core term/tty-colors frame minibuffer cl-generic cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european
ethiopic indian cyrillic chinese composite charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray
cl-preloaded nadvice button loaddefs faces cus-face pcase macroexp files
window text-properties overlay sha1 md5 base64 format env code-pages
mule custom widget hashtable-print-readable backquote threads dbusbind
inotify lcms2 dynamic-setting system-font-setting font-render-setting
cairo move-toolbar gtk x-toolkit x multi-tty make-network-process
nativecomp emacs)

Memory information:
((conses 16 123914 7697)
 (symbols 48 8538 1)
 (strings 32 27224 3373)
 (string-bytes 1 883468)
 (vectors 16 16711)
 (vector-slots 8 323004 11886)
 (floats 8 29 34)
 (intervals 56 11155 0)
 (buffers 984 14))