feat(clipboard): allow pasting markdown and html files from the system to the editor

[EchoEllet]

Description

Allow pasting markdown and HTML files into the editor from the system files.

At the moment, if you try to copy a file from the system on the desktop, and paste it into the editor, you will get the file name, this PR aims to use super_clipboard and existing Markdown & HTML converting functionality

Even though this is not directly related to this PR, Markdown, and HTML converting from and to Delta are currently far from perfect, the current implementation could improved a lot however it will likely not work like expected, due to differences between Html and Delta, see this comment for more info.

If the Markdown and HTML implementation improved or changed, no changes are required to QuillController

The following example for copying a Markdown file:

Before

After

This PR also includes changes that are not related such as the use of onError callback from super_clipboard in SuperClipboardService implementation

Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I titled the PR using Conventional Commits.
• I did not modify the CHANGELOG.md nor the package version in pubspec.yaml files.
• All existing and new tests are passing.
• I have run the commands in ./scripts/before_push.sh and it all passed successfully

Breaking Change

Does your PR require developers to manually update their apps to accommodate your change?

• Yes, this is a breaking change (please indicate that with a ! in the title as explained in Conventional Commits).
• No, this is not a breaking change.

[EchoEllet]

@singerdmx
Let me know if you want to revert or leave notes on additional changes.