Allow code-eval plugin using code actions in addition to a code lens

[noinia]

Is your enhancement request related to a problem? Please describe.

I'm using eglot in emacs as my lsp-client. However, eglot does not support code-lenses, just code actions. That means it is currently impossible to use e.g. the eval plugin to evaluate code snippets.

Describe the solution you'd like

I would like to be able to use the eval as a code action; e.g. when the cursor is over foo/or maybe just when 'foo 5' is selected in a piece of code like:

-- >>> foo 5 
--

I want hls to give my 'evaluate foo 5' as a code action (rather than/instead of) a code lens.

Describe alternatives you've considered

The alternative would be to implement and integrate code-lenses into eglot / emacs. However,

1. since this pr has been open for quite a while, that does not really seem to move all that much, but maybe more importantly
2. Even with lsp-mode I find the lens-actions overlays to show e.g. "evaluate" and/or type lenses fairly disruptive; (as e.g. it requires clicking on it), I think having eval be available as a code-action will make for much better integration into e.g. emacs/eglot (and potentially other mostly keyboard oriented editors).

Additional context

Since this functionality seems to already mostly exist in form of a code-lens, I'm optimistically hoping it would not be too much work to add this. I'd be happy to help implement it; but I simply wanted to raise an issue first to see if there are fundamental reasons why providing eval as a code-action (in addition to) a code-lens is undesirable.

[michaelpj]

Duplicate of #496?

Generally I do agree it would be nice if all code lenses were also available as code actions.