Fix maskable icon setting behaviour based on site icon

[thelovekesh]

This is a follow-up to #304 and was originally discussed in #304 (comment).

This PR aims to:

• Add logic to hide the Maskable Icon checkbox if site icon is not set.
• Add logic to remove checked from Maskable Icon checkbox if the user has removed the site icon.

[codecov-commenter]

Codecov Report

Merging #770 (d19d86e) into develop (441f16f) will increase coverage by 0.05%.
The diff coverage is 76.92%.

@@              Coverage Diff              @@
##             develop     #770      +/-   ##
=============================================
+ Coverage      18.96%   19.01%   +0.05%     
  Complexity       346      346              
=============================================
  Files             57       57              
  Lines           2320     2324       +4     
=============================================
+ Hits             440      442       +2     
- Misses          1880     1882       +2     

Flag	Coverage Δ
php	19.01% <76.92%> (+0.05%)	⬆️
unit	19.01% <76.92%> (+0.05%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
wp-includes/class-wp-web-app-manifest.php	66.37% <71.42%> (-0.15%)	⬇️
wp-includes/class-wp-customize-manager.php	88.88% <83.33%> (-3.12%)	⬇️

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[westonruter]

This does capture @pooja-muchandikar's comment in #304 (comment):

If Site icon was set and set as maskable and then removed the site icon, Maskable Icon setting remains checked.

However, I didn't think this was necessarily a bug. It's just whether one thinks of the maskable property being linked to the icon, or if maskable is something that you would persist across icon changes.

[thelovekesh]

However, I didn't think this was necessarily a bug.

Agreed, rather it is just a check to ensure that by default we are assuming that an icon is maskable.

If we had to save maskable property in an icon meta then we will be able to guess it correctly, for an icon maskable property should be true or not, but saving maskable property in meta could be overkill IMO.

[westonruter]

In d19d86e I've addressed @pooja-muchandikar's point in #304 (comment):

• Maskable checkbox is in place but when the checkbox is checked from customizer, an error is shown on manifest, ideally it should show any error. Also the same error is displayed twice any reason?
  

Now when I set the maskable checkbox, I no longer get the warnings:

DevTools seems to group the icons with duplicate dimensions horizontally (although it strangely doesn't automatically apply the mask to them).

[pooja-muchandikar]

QA Passed ✅

No warnings are displayed if maskable checkbox is checked.

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Backend settings are also working fine as expected.

Screen.Recording.2022-04-25.at.9.56.40.AM.mov