Allow copying own text messages when content protection is enabled

[ArtinEB]

Summary

• When a chat/user has "restrict saving content" enabled, the Copy option is currently hidden for every message, including ones the current user authored themselves.
• The only way to get your own text out in that situation was an inconsistent workaround: tap Edit on the message and copy the text from the input field, which was never subject to the same restriction.
• This adds an isOutOwner() exception to the Copy gating in the single-message long-press menu and the multi-select action bar, so the message's author can copy their own text/caption directly.

What is NOT changed

• Forwarding and media saving remain fully restricted for everyone (untouched).
• Copy remains hidden for messages authored by other users/channels.
• Only text-ish content types are affected (text, caption, dice, animated emoji) — matching the existing Copy conditions.

Test plan

• In a group/channel with "restrict saving content" enabled, long-press your own text message → Copy is visible and copies the text.
• Long-press another user's message in the same chat → Copy is still hidden.
• Multi-select (select several of your own text messages) → Copy button in the action bar appears and copies them.
• Multi-select mixing your own and others' messages → only your own messages are copied.
• Forward and Save-to-gallery/document remain disabled everywhere in the restricted chat.