* feat: add `source.filter` config
This allows the user to specify a `filter` function for each source,
like this:
```lua
-- don't show entries with kind "Text" from the "nvim_lsp" source
sources = {
{
name = "nvim_lsp",
filter = function(entry, ctx)
local kind = types.lsp.CompletionItemKind[entry:get_kind()]
if kind == "Text" then
return true
end
},
}
```
By utilizing the `ctx` parameter, the user can also ignore certain
entries in certain contexts.
* fixup! feat: add `source.filter` config
* fixup! feat: add `source.filter` config