Cookie: add input validation

[jrfnl]

Cookie::__construct(): add input validation

This commit adds input validation for all parameters of the Cookie::__construct() method:

• For $name and $value, I've chosen to only accept plain strings and not Stringable objects.
• The $attributes parameter accepts an array or an instance of CaseInsensitiveDictionary according to the docs, but the important thing about the CaseInsensitiveDictionary part is that if the parameter is passed as an object, it needs to have both ArrayAccess, as well as be Traversable, so the input validation checks for those characteristics rather than hard-requiring an instance of CaseInsensitiveDictionary.
• As the $flags parameter is used with array_merge(), we cannot accept objects, so an array is the only valid input type.
• As for $reference_time: as the default value is set using time(), which returns an integer time stamp, I've implemented the input validation to expect an integer.

Includes tests for these new exceptions.

Cookie::domain_matches(): add input validation

As this method only returns boolean, we may as well return boolean false instead of throwing an exception.

Includes tests.

Cookie::path_matches(): add input validation

As this method only returns boolean, we may as well return boolean false instead of throwing an exception.

The input validation in this case is not done at the very start of the function to prevent changing the behaviour of the function for those cases which were already being handled by the method. This is also the reason for using is_scalar() instead of is_string().

Includes tests.

Cookie::parse(): add input validation

This adds input validation to the Cookie::parse() method for the $cookie_header and $name parameters.

As the $reference_time parameter is not directly used in this method, but only passed through to the Cookie::__construct() method, no input validation has been added, as it will be validated by the Cookie::__construct() method.

Includes tests for the new exceptions + a test to safeguard that the "fall through validation for the $reference_time" actually happens.

Includes fixing up two tests which were passing the wrong value type for an optional parameter.

Cookie::parse_from_headers(): add test safeguarding input validation

The first and second argument for the Cookie::parse_from_headers() method already have (class-based) type declarations.
The third argument - $time - is only used to pass it through to the parse() method, which will subsequently pass it through to the class constructor which contains input validation for the parameter.

This just adds a test to safeguard that the "fall through" validation for the $time parameter actually happens.

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Regarding the other public methods:

• The uri_matches() method already has a class based type declaration.
• The other public methods do not take parameters.