feat: allow a callback to be called on on_lines update (for filtering tags from query text) (#455)

* allow a callback to be called on on_lines update

* .

* remove unused _filter_marker var

* nit: Move to table and implement 'close'

Co-authored-by: TJ DeVries <devries.timothyj@gmail.com>

lua/telescope/pickers.lua

@@ -76,6 +76,7 @@ function Picker:new(opts)
 
     default_text = opts.default_text,
     get_status_text = get_default(opts.get_status_text, config.values.get_status_text),
+    _on_input_filter_cb = opts.on_input_filter_cb or function() end,
 
     finder = opts.finder,
     sorter = opts.sorter,
@@ -445,7 +446,17 @@ function Picker:find()
       return
     end
 
-    local prompt = self:_get_prompt()
+    local original_prompt = self:_get_prompt()
+    local on_input_result = self._on_input_filter_cb(original_prompt) or {}
+
+    local prompt = on_input_result.prompt or original_prompt
+    local finder = on_input_result.updated_finder
+
+    if finder then
+      self.finder:close()
+      self.finder = finder
+    end
+
     if self.sorter then
       self.sorter:_start(prompt)
     end