The `rand-quote` plugin uses quotationspage.com and prints part of its content to the
shell without sanitization, which could trigger command injection. There is no evidence
that this has been exploited, but this commit removes all possibility for exploit.

Similarly, the `hitokoto` plugin uses the hitokoto.cn website to print quotes to the
shell, also without sanitization. Furthermore, there is also no evidence that this has
been exploited, but with this change it is now impossible.

- Make function variables local
- Use prompt color sequences
- Use guard clause to check for curl
- Improved syntax

Fixes #6949

Gaaah.

This plugin was designed so that if there is any failure, it will simply call itself recursively. Which means that if you were working offline, if `quote` was called in your `.zshrc`, you would be unable to open a new terminal session.

I fixed this by allowing the plugin to output nothing if a quote could not be fetched.

correcting an issue about encoding some people was having
added a message when the user doesn't have curl
added varibles for colors->easier to customize