allow regex or custom function in the keywords for plugins

[a3chron]

this is the color plugin, currently you have to type in hex, press enter, and then paste or type the color-code you need to convert or see.

Most users, or me at least usually just want to open bs via hotkey, and paste a hex value.

In this case, it would be great, if somehow we could make an option for plugins to show right at the "command level", i.e. on input plugins could either via regex (would be easier ig) or custom functions (but security concerns and probably harder to implement) or some other acceptable way detect patterns they want to show an output for.
Options 1:

• For the example with the color plugin, it would just detect a # followed by 3 or 6 numbers, and show a "#F04C00" for example if that was the input, and if the user would select this option besides the other commands, it would show an info field for example, just like described in Allow an extra info field for the currently selected option #43.
  Example:

Option 2:

• probably easier to implement, just the regex / function / sth, to make the plugin show up there, and the user could select this option right away
  Example:

Another option is of course, instead of writing plugins for such things, one would just add them to backslash, just like in this Pr for math #38

[a3chron]

Another option is of course, instead of writing plugins for such things, one would just add them to backslash, just like in this Pr for math #38

Alr, after thinking about it, this should work, there should not be that much plugins that need this, or at least not much I thought of right away, so this can be if needed implemented just like the mentioned math command