feat!: new @sync peek annotation for sync previewers

[sxyazi]

After this PR, the runtime environment of the previewer (synchronous or asynchronous) will be distributed as metadata together with the source code.

This means that when a plugin needs to change the runtime, it will no longer require users to modify it in their yazi.toml.

⚠️ Breaking changes

sync = true has been removed:

# yazi.toml
[plugin]
prepend_previewers = [
-  { name = "*/", run = "folder", sync = true },
+  { name = "*/", run = "folder" },
]

and replaced with the new --- @sync peek annotation:

# ~/.config/yazi/plugins/folder.yazi/main.lua
+ --- @sync peek

Considering that except for the preset folder previewer, almost all previewers are asynchronous, the impact of this change should be reasonably small.

Doc https://yazi-rs.github.io/docs/plugins/overview#@sync