Remove top app bar scroll behavior

This lets us make it more consistent with the Compose screens for now. Maybe it'll return in the future.

This also includes making the AboutController a full Compose controller with a new abstracted TopAppBar composable.

app/src/main/java/eu/kanade/presentation/components/AppBar.kt

@@ -1,12 +1,15 @@
 package eu.kanade.presentation.components
 
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.RowScope
 import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.ArrowBack
 import androidx.compose.material.icons.filled.MoreVert
 import androidx.compose.material3.DropdownMenuItem
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.SmallTopAppBar
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
@@ -19,6 +22,30 @@ import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextOverflow
 import eu.kanade.tachiyomi.R
 
+@Composable
+fun TopAppBar(
+    title: String?,
+    subtitle: String? = null,
+    navigateUp: () -> Unit,
+    navigationIcon: ImageVector = Icons.Default.ArrowBack,
+    actions: @Composable RowScope.() -> Unit = {},
+) {
+    SmallTopAppBar(
+        navigationIcon = {
+            IconButton(onClick = navigateUp) {
+                Icon(
+                    imageVector = navigationIcon,
+                    contentDescription = stringResource(R.string.abc_action_bar_up_description),
+                )
+            }
+        },
+        title = {
+            AppBarTitle(title, subtitle)
+        },
+        actions = actions,
+    )
+}
+
 @Composable
 fun AppBarTitle(
     title: String?,