Fix: Add Exit Toast

[prit29]

Closes #372

What has been done to verify that this works as intended?

I tested it on Android 9.0.

Why is this the best possible solution? Were any other approaches considered?

As comments in this issue, I figure out that exit confirmation is good, but not by dialog so I'm doing this by an easy approach.

How does this change affect users? Describe intentional changes to behavior and behavior that could have accidentally been affected by code changes. In other words, what are the regression risks?

No regression risks

Before submitting this PR, please make sure you have:

• [x] run ./gradlew checkCode and confirmed all checks still pass OR confirm CircleCI build passes
• [x] verified that any code or assets from external sources are properly credited in comments and/or in the about file.

[ajay-prabhakar]

@pritsahkar You still can work on the previous PR, if you got stuck at anywhere we are happy to help you As you opened new PR please close the previous one

[prit29]

you are getting Do not use Windows line endings In windows android studio will have the new lines at the end you can change that in settings for that please follow these steps and run once again

• Change line endings to Unix. Settings > Editor > Code Style > General (tab) > Line Separator :: Unix and Mac OS (\n)

@Chromicle I already do it, but still give an error, I think I should change all files CRLF to LF and add a commit... and thanks for your suggestions & response

[ajay-prabhakar]

@pritsahkar are you still working on this?

[ajay-prabhakar]

@huangyz0918 as there is no response I think you close this