fix: Message alerts for image upload using image upload button and url button

[amishabagri]

What type of PR is this?

bug

What this PR does / why we need it:

This Pull request addresses the issue of issue #4494 where even if the image upload fails no message or alert was displayed.
This also covers the issue related to the URL. If URL of the image is provided, it didn't use to check if the URL is valid or not and consequently did not displayed any message. So through this PR request the following things are covered:

1. When uploading the image the .file is checked if it is valid or not. If the file ends with .jpg, .jpeg, .png etc, the image file is accepted and is uploaded. After uploading the file the message is also displayed.
2. If the image extension is not same as the .jpg, .png, etc, then the error message is diplayed for using wrong file extension.
3. For using the URL,, the URL is checked if it is valid or not using the HTTP codes. If the URL is valid, the image is uploaded and the success message is displayed.
4. If the URL is not valid, then the error message is displayed.

Before: No messages are displayed

1. Uploading with a URL

2. Uploading with Upload Image button

After: Messages are displayed

1. Uploading when URL is invalid

2. When URL is valid and image is also changed:

3. Using valid file extension:

4. Using invalid file extension:

Which issue(s) this PR fixes:

Fixes #4494

Testing

Since this was changes in UI, I tested with different URLs , valid and invalid to verify if the message is displayed.
I tested with different file extension to make see if there is invalid file extension the message is displayed.

Note:

Please ignore the WakelockSwitch.vue

[Kuchenpirat]

Hey, thanks for your contribution.

I just had a quick glance at it and this looks mostly good. I just have one thing to add and a few minor code comments for my first feedback round.

The Image button is no longer properly aligned with the settings button. This would need to be updated.

[amishabagri]

I have made the changes. Please review it