Direct Message [Action Sheet]: add Action sheet for a DM conversation

Fixes zulip#1272

Author: Abhisheksainii

assets/l10n/app_en.arb

@@ -680,5 +680,9 @@
   "emojiPickerSearchEmoji": "Search emoji",
   "@emojiPickerSearchEmoji": {
     "description": "Hint text for the emoji picker search text field."
+  },
+  "showUsersInDM": "Show users in DM",
+  "@showUsersInDM": {
+    "description": "Label for showing users in DM through DM Action Sheet"
   }
 }

lib/api/model/model.dart

@@ -875,3 +875,8 @@ enum MessageEditState {
     return MessageEditState.none;
   }
 }
+
+enum DMActionSheetOption{
+  markAsRead,
+  groupDmUsers,
+}

lib/generated/l10n/zulip_localizations.dart

@@ -1014,6 +1014,12 @@ abstract class ZulipLocalizations {
   /// In en, this message translates to:
   /// **'Search emoji'**
   String get emojiPickerSearchEmoji;
+
+  /// Label for showing users in DM through DM Action Sheet
+  ///
+  /// In en, this message translates to:
+  /// **'Show users in DM'**
+  String get showUsersInDM;
 }
 
 class _ZulipLocalizationsDelegate extends LocalizationsDelegate<ZulipLocalizations> {

lib/generated/l10n/zulip_localizations_ar.dart

@@ -537,4 +537,7 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get showUsersInDM => 'Show users in DM';
 }

lib/generated/l10n/zulip_localizations_en.dart

@@ -537,4 +537,7 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get showUsersInDM => 'Show users in DM';
 }

lib/generated/l10n/zulip_localizations_fr.dart

@@ -537,4 +537,7 @@ class ZulipLocalizationsFr extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get showUsersInDM => 'Show users in DM';
 }

lib/generated/l10n/zulip_localizations_ja.dart

@@ -537,4 +537,7 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get showUsersInDM => 'Show users in DM';
 }

lib/generated/l10n/zulip_localizations_pl.dart

@@ -537,4 +537,7 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get showUsersInDM => 'Show users in DM';
 }

lib/generated/l10n/zulip_localizations_ru.dart

@@ -537,4 +537,7 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
 
   @override
   String get emojiPickerSearchEmoji => 'Search emoji';
+
+  @override
+  String get showUsersInDM => 'Show users in DM';
 }