Fix: Lingering DRM dialog when Learn more link clicked

[0nko]

Task/Issue URL: https://app.asana.com/1/137249556945/project/1207418217763355/task/1217714992339528?focus=true

Description

This PR solves an issue when the DDG is the default browser and a user clicks on the DRM dialog's Learn more link, which leaves the DRM dialog open on top of the wrong tab.

Steps to test this PR

• Set DDG as a default browser
• Load some site that displays a DRM dialog (https://reference.dashif.org/dash.js/latest/samples/drm/widevine.html)
• Tap on the "Learn more" link
• Notice the dialog is dismissed when the website is loaded

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Note

Low Risk
Small UX fix in the DRM permission dialog click path; it now denies the in-session request when Learn more is opened, with no auth or persistence changes.

Overview
Fixes the DRM site-permission dialog lingering over a new tab when the user taps Learn more while DuckDuckGo is the default browser.

The Learn more click handler now dismisses the dialog and denies the pending DRM request before opening the help URL, so the permission prompt is not left unanswered on the original page. Adds a Robolectric test (with Android resources enabled for the module) covering that path.

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[anikiki]

Looks good and works as expected! 🎉