Zsh: consider first class support for `romkatv/zsh-defer`

[rossmacarthur]

romkatv/zsh-defer is a great Zsh plugin that can basically give zinit's turbo mode to any plugin manager. It might be cool to provide support for deferring plugin sourcing out of the box using this plugin.

You can still very easily use this plugin using the following.

[templates]
defer = { value = 'zsh-defer source "{{ file }}"', each = true }

[plugins.zsh-defer]
github = "romkatv/zsh-defer"

And then you just have to add apply = ["defer"] to any plugin you want to defer source ...

I propose adding the following

• Add defer as default template
• if someone has not overriden defer and uses it then automatically add romkatv/zsh-defer as a plugin.

[rossmacarthur]

I think documentation on how to achieve this is sufficient. https://rossmacarthur.github.io/sheldon/Examples.html#deferred-loading-of-plugins-in-zsh