Convert all TopBottomPanel with Panel, and remove reference to TopBottomPanel when both SidePanel and TopBottomPanel were mentioned.

following those steps:
1. Rename `egui::TopBottomPanel` with `egui::Panel`.
2. Rename `height` with `size` in all chained methods.
    - `default_height()` to `default_size()`
    - `min_height()` to `min_size()`
    - `max_height()` to `max_size()`
    - `height_range()` to `size_range()`
    - `exact_height()` to `exact_size()`

if using `Panel::new()`, replace
- `TopBottomSide::Top` with `Side::Horizontal(HorizontalSide::Top)`
- `TopBottomSide::Bottom` with `Side::Horizontal(HorizontalSide::Bottom)`

NOTE: Non-working commit

crates/egui_demo_lib/src/demo/demo_app_windows.rs

@@ -224,7 +224,7 @@ impl DemoWindows {
     }
 
     fn mobile_top_bar(&mut self, ctx: &Context) {
-        egui::TopBottomPanel::top("menu_bar").show(ctx, |ui| {
+        egui::Panel::top("menu_bar").show(ctx, |ui| {
             egui::menu::bar(ui, |ui| {
                 let font_size = 16.5;
 
@@ -279,7 +279,7 @@ impl DemoWindows {
                 self.demo_list_ui(ui);
             });
 
-        egui::TopBottomPanel::top("menu_bar").show(ctx, |ui| {
+        egui::Panel::top("menu_bar").show(ctx, |ui| {
             egui::menu::bar(ui, |ui| {
                 file_menu_button(ui);
             });

crates/egui_demo_lib/src/demo/panels.rs

@@ -22,9 +22,9 @@ impl crate::View for Panels {
     fn ui(&mut self, ui: &mut egui::Ui) {
         // Note that the order we add the panels is very important!
 
-        egui::TopBottomPanel::top("top_panel")
+        egui::Panel::top("top_panel")
             .resizable(true)
-            .min_height(32.0)
+            .min_size(32.0)
             .show_inside(ui, |ui| {
                 egui::ScrollArea::vertical().show(ui, |ui| {
                     ui.vertical_centered(|ui| {
@@ -60,9 +60,9 @@ impl crate::View for Panels {
                 });
             });
 
-        egui::TopBottomPanel::bottom("bottom_panel")
+        egui::Panel::bottom("bottom_panel")
             .resizable(false)
-            .min_height(0.0)
+            .min_size(0.0)
             .show_inside(ui, |ui| {
                 ui.vertical_centered(|ui| {
                     ui.heading("Bottom Panel");

crates/egui_demo_lib/src/easy_mark/easy_mark_editor.rs

@@ -33,7 +33,7 @@ impl Default for EasyMarkEditor {
 
 impl EasyMarkEditor {
     pub fn panels(&mut self, ctx: &egui::Context) {
-        egui::TopBottomPanel::bottom("easy_mark_bottom").show(ctx, |ui| {
+        egui::Panel::bottom("easy_mark_bottom").show(ctx, |ui| {
             let layout = egui::Layout::top_down(egui::Align::Center).with_main_justify(true);
             ui.allocate_ui_with_layout(ui.available_size(), layout, |ui| {
                 ui.add(crate::egui_github_link_file!())