Add support for Trusted Types CSP

[LuizGustavoMagalhaes]

Is your feature request related to a problem? Please describe.
We're trying to implement Trusted types CSP in our Web Application (which uses OverlayScrollbars) and we're hitting an issue due to the unsafe assignment on

OverlayScrollbars/packages/overlayscrollbars/src/support/dom/create.ts

Line 21 in 998cc58

createdDiv.innerHTML = html.trim();

You can find more details here:
https://web.dev/articles/trusted-types

Describe the solution you'd like
For fixing it, you can create a custom policy that only allows that values that are set within the library. Something like

let overlayScrollbarsTrustedTypesPolicy: Pick<TrustedTypePolicy, 'createHTML'> | undefined;
if (window.trustedTypes) {
    overlayScrollbarsTrustedTypesPolicy= window.trustedTypes.createPolicy(
        'overlayScrollbarsTrustedTypesPolicy',
        {
            createHTML: (url: string) => {
                if (
                    url === '<div class=\"os-environment\"><div></div></div>'
                ) {
                    return url;
                }
                // The URL is not allowed, return an empty string
                return '';
            },
        }
    );
}
export { iFrameDocumentTrustedTypesPolicy };

And then apply the policy in the location we're getting the issue

export const createDOM = (html: string): ReadonlyArray<Node> => {
    const createdDiv = createDiv();
    createdDiv.innerHTML =
        (overlayScrollbarsTrustedTypesPolicy?.createHTML(html.trim()) as unknown as string) ?? html.trim();

    return each(contents(createdDiv), elm => removeElements(elm));
};

[KingSora]

@LuizGustavoMagalhaes Good day :)

Thanks for the suggestion! I'll definitely add something like this, probably the design will look something like the current OverlayScrollbars.nonce api. With the naming of OverlayScrollbars.trustedTypesPolicy(newTurstedTypePolicy)

I'll look into the trusted types api first though as I'm not very familiar with it yet and TypeScript doesn't offer any types.