Trusted Types / CSP: jsPDF blocked with "This document requires 'TrustedHTML' assignment" — add TrustedTypes policy support

Short description

When pages enforce Trusted Types via CSP, jsPDF is blocked and throws:

Failed to execute 'write' on 'Document': This document requires 'TrustedHTML' assignment.

Cause: jsPDF writes HTML strings into the DOM (e.g. document.write, innerHTML) without producing TrustedHTML via a Trusted Types policy. Under CSPs that require trusted types, these operations are rejected.

Expected behaviour

jsPDF should work on pages that enforce Trusted Types. Concretely, jsPDF should:

• Detect Trusted Types support and create or use a configurable Trusted Types policy.
• Use that policy to produce TrustedHTML (and other Trusted Types if needed) before calling DOM APIs that require it.
• Expose a way for integrators and third-party plugins to reuse the same policy name/instance.

This allows an application to enable jsPDF under a restrictive CSP such as: Content-Security-Policy: require-trusted-types-for 'script'; trusted-types jsPDF;