Add PHPStan

[HardeepAsrani]

All Submissions:

• Have you followed the Optimole Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

This adds PHPStan to level 5 and changes have been made to best of my knowledge, so it will be good to have a review to make sure no changes are reverting intended code.

Also, there is one error left in PHPStan which I'm not able to realize why that particular line of code was written the way it is written so feedback there is appreciated.

Closes #566.

How to test the changes in this Pull Request:

1. Just make sure everything works as before in Optimole plugin.
2. Most importantly to test all the settings about including/excluding.
3. Make sure to have debugging on and make sure there isn't anything in the debug logs.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?

[pirate-bot]

Plugin build for b41a949 is ready 🛎️!

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[GrigoreMihai]

@HardeepAsrani Regarding the error you mentioned I did some tests and the type of $width is an integer there. I used the gettype to get the type of the var.

It's safe to change the type on the function param declaration to integer for $width and it should fix the phpstan error.

[abaicus]

@HardeepAsrani I think other than what @GrigoreMihai mentioned, this should be ok to go 👍🏻 Thanks for addressing all the other issues! 🚀

[irinelenache]

@HardeepAsrani Tested the PR and didn't find any problem 🚀

[pirate-bot]

🎉 This PR is included in version 3.8.2 🎉

The release is available on GitHub release

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