Fix bullet points not having leading margin on timeline items (#4536)

* Fix bullet points not having leading margin on timeline items

* Remove other usages of `SpannableString` constructor, use either `valueOf` to reuse the existing value or `SpannedString` instead if the spans don't have to change

libraries/textcomposer/impl/src/main/kotlin/io/element/android/libraries/textcomposer/components/markdown/StableCharSequence.kt

@@ -16,11 +16,11 @@ import io.element.android.libraries.core.extensions.orEmpty
 
 @Stable
 class StableCharSequence(initialText: CharSequence = "") {
-    private var value by mutableStateOf<SpannableString>(SpannableString(initialText))
+    private var value by mutableStateOf<SpannableString>(SpannableString.valueOf(initialText))
     private var needsDisplaying by mutableStateOf(false)
 
     fun update(newText: CharSequence?, needsDisplaying: Boolean) {
-        value = SpannableString(newText.orEmpty())
+        value = SpannableString.valueOf(newText.orEmpty())
         this.needsDisplaying = needsDisplaying
     }
 

libraries/textcomposer/impl/src/main/kotlin/io/element/android/libraries/textcomposer/model/MarkdownTextEditorState.kt

@@ -9,7 +9,6 @@ package io.element.android.libraries.textcomposer.model
 
 import android.os.Parcelable
 import android.text.Spannable
-import android.text.SpannableString
 import android.text.SpannableStringBuilder
 import android.text.Spanned
 import androidx.compose.runtime.Composable
@@ -118,8 +117,7 @@ class MarkdownTextEditorState(
     }
 
     fun getMentions(): List<IntentionalMention> {
-        val text = SpannableString(text.value())
-        val mentionSpans = text.getMentionSpans()
+        val mentionSpans = text.value().getMentionSpans()
         return mentionSpans.mapNotNull { mentionSpan ->
             when (mentionSpan.type) {
                 is MentionType.User -> IntentionalMention.User(mentionSpan.type.userId)