Make querystring available in load()

[icalvin102]

Describe the problem

The page.query in the load function is a instance of URLSearchParams which is fine for cases that use standard queries.
However there are many commonly used ways to use the query of a URL that do not work well with URLSearchParams.

Using comma separated values for example is a commonly used practice that can fail with URLSearchParams.

Consider the following example:

const categories = [
'articles',
'cats,dogs'
];

const querystring = `categories=${categories.map(encodeURIComponent).join(',')}`;

console.log(querystring);
console.log((new URLSearchParams(querystring)).toString());

// Console output
// categories=articles,cats%2Cdogs
// categories=articles%2Ccats%2Cdogs

The output is clearly not the same and it is impossible to get the correct value from the instance of URLSearchParams.
The input should be interpreted as a array of length 2 with the contents articles, cats,dogs but it gets interpreted as a array of length 3 with the values articles, cats, dogs.

Describe the proposed solution

Pass a page.querystring property with the unparsed querystring alongside with page.query to the load function.

Alternatives considered

On the client the location.search can be used instead of page.query but this is not available on the server.

Importance

would make my life easier

Additional Information

No response

[icalvin102]

Implemented by #3133 which makes the whole URL object available in load.
The querystring can now be accessed trough url.search