[ZEPPELIN-391] Keyboard shortcut

[Leemoonsoo]

What is this PR for?

This PR implements keyboard shortcuts for paragraph control.

What type of PR is it?

Feature

Is there a relevant Jira issue?

https://issues.apache.org/jira/browse/ZEPPELIN-391

How should this be tested?

Try implemented shortcuts

Ctrl + Alt + c : Cancel run
Ctrl + Alt + d : Remove paragraph
Ctrl + Alt + k : Move paragraph Up
Ctrl + Alt + j : Move paragraph Down
Ctrl + Alt + b : Insert new paragraph below
Ctrl + Alt + o : Toggle output
Ctrl + Alt + e : Toggle editor
Ctrl + Alt + m : Toggle line numbers
Ctrl + Alt + t : Toggle title
Ctrl + Alt + 10,-,+ : Paragraph width from 112

Questions:

• Does the licenses files need update? no
• Is there breaking changes for older versions? no
• Does this needs documentation? no

[Leemoonsoo]

Please review

[minahlee]

Ctrl + c is commonly used to copy highlighted text to the clipboard so better to change.

[Leemoonsoo]

@minahlee You're right. Changed to Ctrl+Alt+c

[minahlee]

Ctrl + Alt + k and Ctrl + Alt + E does work on chrome, firefox but not on IE

[Leemoonsoo]

@minahlee Some more shortcuts are not working in IE. for example Ctrl + n, Ctrl + p.
Do you mind handle shortcuts on IE separately?

[minahlee]

@Leemoonsoo sure

[Leemoonsoo]

I'll create an issue for shortcut on IE.
Merge if there're no more discussions