[Rich text editor] Add full screen mode (#1447)

- Add full screen mode for the rich text editor (RTE). When text formatting options are enabled, the editor can be dragged to full screen.
- Remove `ConstraintLayout` from `textcomposer` module, now made much simpler now the RTE supports being called in multiple layouts matrix-org/matrix-rich-text-editor#822

- Part of vector-im/element-meta#1973
- Includes design from #1315
- Fixes #1293 (through new layout)
- Fixes #1394 (through inclusion of matrix-org/matrix-rich-text-editor#824)
- Fixes #1259 (through inclusion of matrix-org/matrix-rich-text-editor#820)

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Co-authored-by: ElementBot <benoitm+elementbot@element.io>

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/theme/components/BottomSheetDragHandle.kt

@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.designsystem.theme.components
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.border
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.offset
+import androidx.compose.foundation.layout.requiredHeight
+import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.RectangleShape
+import androidx.compose.ui.unit.dp
+import io.element.android.libraries.designsystem.preview.ElementPreview
+import io.element.android.libraries.designsystem.preview.PreviewsDayNight
+import io.element.android.libraries.theme.ElementTheme
+
+@Composable
+fun BottomSheetDragHandle(
+    modifier: Modifier = Modifier
+) {
+    Box(
+        modifier = modifier
+            .height(36.dp)
+            .background(Color.Transparent)
+            .fillMaxWidth()
+            .clip(RectangleShape),
+        contentAlignment = Alignment.Center
+    ) {
+        Box(
+            modifier = Modifier
+                .fillMaxWidth()
+                .requiredHeight(72.dp)
+                .offset(y = 18.dp)
+                .clip(MaterialTheme.shapes.extraLarge)
+                .background(MaterialTheme.colorScheme.background)
+                .border(0.5.dp, ElementTheme.colors.borderDisabled, MaterialTheme.shapes.extraLarge)
+        )
+
+        Box(
+            modifier = Modifier
+                .width(32.dp)
+                .height(4.dp)
+                .background(ElementTheme.colors.iconQuaternary, RoundedCornerShape(2.dp))
+        )
+    }
+}
+
+
+@PreviewsDayNight
+@Composable
+internal fun BottomSheetDragHandlePreview() = ElementPreview {
+    BottomSheetDragHandle()
+}