feat: mobile tool bar basic features

[hyj1204]

1. Build basic structure for toolbar items in mobile.

Currently, there has two types of MobileToolbarItem: action and withMenu. action is for the feature which implement directly after click the toolbar Item, like code inline. withMenu is for the one needs to open a menu then implement features, like textDecorationMobileToolbarItem

2. Add the following toolbar items.

When the selection changes, MobileToolbarWidget gets rebuilt based on the current/updated selection(all the item menus will be closed).

All the testing code of following checked features have been added.

The unchecked features will be add in other PRs in the future.

MobileToolbarItem	Sub buttons on its menu
textDecoration	bold	✔️
	italic	✔️
	underline	✔️
	strikethrough	✔️
colorDecoration	text color picker	ToDo
	highlight color picker	ToDo
code	None	✔️
link	link input	✔️
	Setting for exist link	Need redesign Same as desktop for now
header	heading 1	✔️
	heading 2	✔️
	heading 3	✔️
list	bulleted list	✔️
	numbered list	✔️
todo list	None	✔️
quote	None	✔️
divider	None	ToDo

Some videoshots, like text decoration and code inline

Screen.Recording.2023-06-02.at.11.14.04.AM.mov

Screen.Recording.2023-06-02.at.11.30.03.AM.mov

3. Add MobileToolbarStyle as InheritedWidget to manage all the cosmetic parameters in MobileToolbar

• To customize the style of MobileToolbar, just give the value directly to MobileToolbar

MobileToolbar(
                  backgroundColor: Colors.white,
                  foregroundColor: Colors.black,
                  itemHighlightColor: Colors.blue,
                  editorState: editorState,
                  toolbarItems: [
                    textDecorationMobileToolbarItem,   
                    linkMobileToolbarItem,
                    codeMobileToolbarItem, 
                  ],

• If no value is provided, it will use the default value here.

• Use MobileToolbarStyle.of(context) to access its cosmetic parameters in child widgets.
  

4. Chores:

• move all the tests in mobile to test/mobile
• move toolbar/items to toolbar/desktop/items

[codecov]

Codecov Report

Merging #161 (11f602c) into main (7fe5bb8) will increase coverage by 4.74%.
The diff coverage is 97.43%.

@@            Coverage Diff             @@
##             main     #161      +/-   ##
==========================================
+ Coverage   58.81%   63.56%   +4.74%     
==========================================
  Files         215      228      +13     
  Lines        9643    10062     +419     
==========================================
+ Hits         5672     6396     +724     
+ Misses       3971     3666     -305     

Impacted Files	Coverage Δ
...lbar/desktop/items/bulleted_list_toolbar_item.dart	80.00% <ø> (ø)
...editor/toolbar/desktop/items/color/color_menu.dart	0.00% <ø> (ø)
...itor/toolbar/desktop/items/color/color_picker.dart	80.24% <ø> (ø)
...ktop/items/color/highlight_color_toolbar_item.dart	83.33% <ø> (ø)
...r/desktop/items/color/text_color_toolbar_item.dart	83.33% <ø> (ø)
...or/toolbar/desktop/items/format_toolbar_items.dart	96.29% <ø> (ø)
...r/toolbar/desktop/items/heading_toolbar_items.dart	73.68% <ø> (ø)
.../toolbar/desktop/items/highlight_toolbar_item.dart	0.00% <ø> (ø)
...editor/toolbar/desktop/items/icon_item_widget.dart	100.00% <ø> (ø)
...c/editor/toolbar/desktop/items/link/link_menu.dart	100.00% <ø> (ø)
... and 21 more

... and 23 files with indirect coverage changes

[LucasXu0]

how about passing the state by the itemMenuBuilder callback instead of using mobileToolbarItemMenuKey?

itemMenuBuilder: (editorState, selection, menuState)

[hyj1204]

I use mobileToolbarItemMenuStateKey to close MobileToolbarItemMenu(make it show a SizedBox.shrink()).
I got confused about how can I get the state of MobileToolbarItemMenu without using Key?

[LucasXu0]

try to remove the global key here.

[LucasXu0]

LGTM