Show options menu & navigation drawer using WebView

[krmanik]

Pull Request template

Purpose / Description

Show options menu using JavaScript in WebView when screen is in fullscreen.
This is continuation of #6307

Fixes

Fixes Link to the issues.

Approach

1. Check if it is in full screen or not
2. Call the function using JavaScript

How Has This Been Tested?

Tested on Emulator

1. Add following to card templates in in <script> tag

<button onclick="ankiShowOptionsMenu()">Show Options Menu</button>
<button onclick="ankiShowNavDrawer()">Show Navigation Drawer</button>

2. Turn on full screen, then click on above button to show menu

Learning (optional, can help others)

https://stackoverflow.com/questions/32643310/getactionbar-returns-null-in-actionbar
https://stackoverflow.com/questions/4642914/is-there-a-way-to-determine-if-android-app-is-running-full-screen

Checklist

Please, go through these checks before submitting the PR.

• [ x ] You have not changed whitespace unnecessarily (it makes diffs hard to read)
• [ x ] You have a descriptive commit message with a short title (first line, max 50 chars).
• [ x ] Your code follows the style of the project (e.g. never omit braces in if statements)
• [ x ] You have commented your code, particularly in hard-to-understand areas
• [ x ] You have performed a self-review of your own code

[krmanik]

This will be useful if AnkiDroid is in fullscreen, then one can be added to open those menu.

[david-allison]

One question, then good to go!

[david-allison]

Thanks!!

[mikehardy]

Pretty soon people will be able to have whatever user interface they want, at least with review :-). LGTM, thanks @infinyte7