Browser: improve keyboard shortcuts

[kycutler]

Closes #290771
Closes #290759
Closes #290645
Closes #290644

[Copilot]

Pull request overview

This PR updates the integrated browser to support more standard browser-style keyboard shortcuts for navigation, reloading, opening tabs, and focusing the URL bar.

Changes:

• Binds Ctrl/Cmd+T (when a browser editor is active) to open a new integrated browser tab via the existing workbench.action.browser.open command.
• Adds Cmd+[ / Cmd+] (via CtrlCmd+BracketLeft/Right) as secondary keybindings for Back/Forward, and switches Reload to use Cmd/Ctrl+R as primary (with F5 secondary) with higher precedence over window reload and debug.
• Introduces FocusUrlInputAction with Ctrl/Cmd+L in the browser editor and exposes BrowserEditor.focusUrlInput() so both new tabs and the keybinding can focus the URL input consistently.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/vs/workbench/contrib/browserView/electron-browser/browserViewActions.ts	Adds new keybindings for open-new-tab, back/forward, reload, and a new FocusUrlInputAction wired to Ctrl/Cmd+L and registered with the browser actions.
src/vs/workbench/contrib/browserView/electron-browser/browserEditor.ts	Routes initial focus for new-in-group editors through a new focusUrlInput() method on BrowserEditor, which delegates to the navigation bar’s URL-input focusing logic.