refactor: remove NFT avatar functionality

Removes avatar-settings component, avatar-visibility store, and all
avatar rendering from posts. Strips avatar from account JSON, renames
NFT gateway label to media IPFS gateway, removes Polygon RPC and
hide-avatars toggle. Deletes 6 avatar-related translation keys.

public/translations/en/default.json

@@ -80,7 +80,6 @@
   "show": "show",
   "saved": "saved",
   "paste_signature": "paste signature",
-  "chain_ticker": "Chain ticker",
   "wallet_address": "Wallet address",
   "copy": "copy",
   "copied": "copied",
@@ -179,10 +178,7 @@
   "user_banned": "User was banned for this post",
   "replies": "replies",
   "links": "links",
-  "avatar": "avatar",
-  "token_address_whitelist": "Token address (<1>whitelist</1> only)",
   "animated_gif": "Animated GIF",
-  "hide_avatars": "Hide avatars",
   "pending": "Pending",
   "failed": "Failed",
   "add": "Add",
@@ -201,11 +197,9 @@
   "reset_changes": "Reset Changes",
   "crypto_address_yours": "Crypto address belongs to this account.",
   "delete_wallet": "Delete Wallet",
-  "delete_avatar": "Delete Avatar",
   "last_bumped": "Last Bumped",
   "fit_expanded_images_to_screen": "Fit expanded images to screen",
   "fit_expanded_images_to_screen_tip": "Limit expanded images to both browser width and height",
-  "hide_avatars_tip": "Don't display avatars next to user display names",
   "choose_file": "Choose File",
   "uploading": "uploading...",
   "no_file_chosen": "No file chosen",