[ADD] l10n_de: add states of germany

Closes #18443
Closes #23656

Co-authored-by: Yenthe V.G <yenthevg@gmail.com>

addons/l10n_de/__manifest__.py

@@ -19,6 +19,7 @@ German accounting chart and localization.
     ],
     'data': [
         'data/account_account_tags_data.xml',
+        'data/res.country.state.csv',
         'data/menuitem_data.xml',
         'views/account_view.xml',
     ],

addons/l10n_de/data/res.country.state.csv

+"id","country_id:id","name","code"
+state_de_bw,de,"Baden-Würtenberg","BW"
+state_de_by,de,"Bayern","BY"
+state_de_be,de,"Berlin","BE"
+state_de_bb,de,"Brandenburg","BB"
+state_de_hb,de,"Bremen","HB"
+state_de_hh,de,"Hamburg","HH"
+state_de_he,de,"Hessen","HE"
+state_de_mv,de,"Mecklenburg-Vorpommern","MV"
+state_de_ni,de,"Niedersachsen","NI"
+state_de_nw,de,"Nordrhein-Westfalen","NW"
+state_de_rp,de,"Rheinland-Pfalz","RP"
+state_de_sl,de,"Saarland","SL"
+state_de_sn,de,"Sachsen","SN"
+state_de_st,de,"Sachsen-Anhalt","ST"
+state_de_sh,de,"Schleswig-Holstein","SH"
+state_de_th,de,"Thüringen","TH"