compose [nfc]: Use realm-relative URL for message link in quoteAndReply

Also, use the same URL type in quoteAndReplyPlaceholder.

In inline links, absolute and relative realm URLs are treated
the same by web and mobile, so better to use the shorter version.

Author: sm-sayedi

lib/model/compose.dart

@@ -213,11 +213,11 @@ String quoteAndReplyPlaceholder(
   PerAccountStore store, {
   required Message message,
 }) {
-  final url = narrowLink(store,
+  final relativeUrl = '#${narrowLinkFragment(store,
     SendableNarrow.ofMessage(message, selfUserId: store.selfUserId),
-    nearMessageId: message.id);
+    nearMessageId: message.id)}';
   return '${userMentionFromMessage(message, silent: true, users: store)} '
-    '${inlineLink('said', url.toString())}: ' // TODO(#1285)
+    '${inlineLink('said', relativeUrl.toString())}: ' // TODO(#1285)
     '*${zulipLocalizations.composeBoxLoadingMessage(message.id)}*\n';
 }
 
@@ -229,18 +229,20 @@ String quoteAndReplyPlaceholder(
 ///     ```quote
 ///     message content
 ///     ```
+/// But with a minor difference in that web uses realm-absolute URL and we use
+/// the shorter realm-relative URL for the message link.
 String quoteAndReply(PerAccountStore store, {
   required Message message,
   required String rawContent,
 }) {
-  final url = narrowLink(store,
+  final relativeUrl = '#${narrowLinkFragment(store,
     SendableNarrow.ofMessage(message, selfUserId: store.selfUserId),
-    nearMessageId: message.id);
+    nearMessageId: message.id)}';
   // Could ask userMentionFromMessage to omit the |<id> part unless the mention
   // is ambiguous… but that would mean a linear scan through all users,
   // and the extra noise won't much matter with the already probably-long
   // message link in there too.
   return '${userMentionFromMessage(message, silent: true, users: store)} '
-    '${inlineLink('said', url.toString())}:\n' // TODO(#1285)
+    '${inlineLink('said', relativeUrl.toString())}:\n' // TODO(#1285)
     '${wrapWithBacktickFence(content: rawContent, infoString: 'quote')}';
 }

test/model/compose_test.dart

@@ -351,11 +351,11 @@ hello
 
     check(quoteAndReplyPlaceholder(
       GlobalLocalizations.zulipLocalizations, store, message: message)).equals('''
-@_**Full Name|123** [said](${eg.selfAccount.realmUrl}#narrow/channel/1-test-here/topic/some.20topic/near/${message.id}): *(loading message ${message.id})*
+@_**Full Name|123** [said](#narrow/channel/1-test-here/topic/some.20topic/near/${message.id}): *(loading message ${message.id})*
 ''');
 
     check(quoteAndReply(store, message: message, rawContent: 'Hello world!')).equals('''
-@_**Full Name|123** [said](${eg.selfAccount.realmUrl}#narrow/channel/1-test-here/topic/some.20topic/near/${message.id}):
+@_**Full Name|123** [said](#narrow/channel/1-test-here/topic/some.20topic/near/${message.id}):
 ```quote
 Hello world!
 ```
@@ -364,11 +364,11 @@ Hello world!
     store.connection.zulipFeatureLevel = 249;
     check(quoteAndReplyPlaceholder(
       GlobalLocalizations.zulipLocalizations, store, message: message)).equals('''
-@_**Full Name|123** [said](${eg.selfAccount.realmUrl}#narrow/stream/1-test-here/topic/some.20topic/near/${message.id}): *(loading message ${message.id})*
+@_**Full Name|123** [said](#narrow/stream/1-test-here/topic/some.20topic/near/${message.id}): *(loading message ${message.id})*
 ''');
 
     check(quoteAndReply(store, message: message, rawContent: 'Hello world!')).equals('''
-@_**Full Name|123** [said](${eg.selfAccount.realmUrl}#narrow/stream/1-test-here/topic/some.20topic/near/${message.id}):
+@_**Full Name|123** [said](#narrow/stream/1-test-here/topic/some.20topic/near/${message.id}):
 ```quote
 Hello world!
 ```