Password Input: disable copy and update `Ctrl+Backspace` behavior

[mek-yt]

I created a small Pinentry UI using gpui-component and noticed that the masked input is missing some key security features.

I would like to tighten up the password input behavior:

• Security: Prevent "Copy" actions (both context menu and keyboard shortcuts) to stop passwords from entering the system clipboard when masked.
• UX: Override default Ctrl+Backspace behavior. Instead of deleting the previous word, it should clear the entire input value before cursor when masked.

Steps to Reproduce:

• Enter text into the Password Input.
• Try to copy the text using the context menu or keyboard shortcuts → Current: Text is copied.
• Place the cursor in the middle of the password and press Ctrl+Backspace → Current: Only a portion of the password is deleted.

I am happy to submit a PR for this if it's acceptable.

Architectural Question:

Should I:

• update the behavior of the existing Input component when mask_toggle is active
• create new behavior flags for the existing Input component
• propose a separate PasswordInput component to keep the general Input logic clean?

[Muhammad-Owais-Warsi]

I believe it would be great if we could implement something like .disable_copy(bool) on inputs for this