Add PrivatizeLocalClassConstantRector to SOLID

[mxr576]

Original PR: #1304

[mxr576]

@TomasVotruba Although I am not sure what is the minimum required PHP version by the SOLID config set. I saw an "Add PHP 7.1 level min" task in the original PR and adding visibility to constants is only supported in >= PHP 7.1.

https://www.php.net/manual/en/language.oop5.constants.php

[TomasVotruba]

The PHP version is checked inside the rule:

rector/packages/SOLID/src/Rector/ClassConst/PrivatizeLocalClassConstantRector.php

Lines 69 to 71 in de9eab4

	if (! $this->isAtLeastPhpVersion('7.1')) {
	return null;
	}

[TomasVotruba]

Thank you for PR!