Add "all" matching strategy

[aca]

Is your feature request related to a problem? Please describe.
While I was developing LSP, I tried to implement completion which is searchable by description(detail in lsp spec).
But with current match strategy, fuzzy, exact, substring, this plugin matcher filters the completion item.

--> request #20: textDocument/completion: {"textDocument":{"uri":"file:///home/rok/zettelkasten/fa9766e6.md"},"position":{"character":4,"line":10}}
<-- result #20: textDocument/completion: [{"label":"asd","detail":"completion test","insertText":"asd"}]

Describe the solution you'd like
Add all match function like this.

local function all_match(prefix, word)
  return true
end

local matching_strategy = {
  all = all_match,
  fuzzy = fuzzy_match,
  substring = substring_match,
  exact = exact_match
}

I haven't looked at how other server provides completion.
But If LSP already has it's own way of matching strategy, I believe there should be an option for this plugin to not to filter the completion items. Correct me if I'm wrong.

[haorenW1025]

Seems reasonable to me. Could you take the effort to make a PR for this?

[aca]

Thanks I will send pr later.