Basic completion item kind suport

[nferhat]

This PR allows the completion menu's style to be more configurable, allowing configurations like this:

The concerned configuration options are:

• editor.completion-item-columns: A list of either name or kind, for the symbol name and a user-defined string for its kind respectively.
• editor.completion-item-kinds: A list of the user-defined strings for completion item kinds. When a kind name is not set, it will use the kind's snake_name form instead (the default before this PR)

completion-item-columns = ["kind", "name"]
[editor.completion-item-kinds]
text = ""
method = ""
function = ""
constructor = ""
field = ""
variable = ""
class = ""
interface = ""
module = ""
property = ""
unit = ""
value = ""
enum = ""
keyword = " "
snippet = ""
color = ""
file = ""
reference = ""
folder = ""
enum_member = ""
constant = ""
struct = ""
event = ""
operator = ""
type_parameter = ""

In addition to this, themes are also concerned. The ui.menu.kind scope is the default, and ui.completion.kind.{name} for each kind, where {name} is the snake_case name of the kind name.

[pascalkuthe]

Can you comeup with a set of icons that don't require a patched font as a default? Otherwise, this feature should have an enable setting that defaults to false. Helix should work out of the box without installing a patched font

[pascalkuthe]

Ah nvm I see that you default to the item name. That is a good default, I like this approach much better than enabling icons by default

[David-Else]

This looks great! Any chance the merge conflicts could be fixed? Also, could you add your optional nerd fonts config to the documentation, maybe to the example config at the top of https://docs.helix-editor.com/configuration.html ?

[nferhat]

Closed in favor of #12151