feat(view): Floating nvim tree window #1377 (#1462)

* Simple mock-up of floating nvim-tree window

* Passing whole table to nvim_open_win()

* Run update-help.sh

* Use vim.api alias

* Add comment to float options

* Added `anchor` to float options

* Enabling float window enforces `actions.open_file.quit_on_open`

* Added documentation

* add view.float.open_win_config, skipping validation

* Made nvim-tree window closes when float is enabled

* Close nvim-tree window when out of focus

* Update help

Co-authored-by: Krzysztof Cieśla <krzysztof.marcin.ciesla@cern.ch>
Co-authored-by: Alexander Courtis <alex@courtis.org>

doc/nvim-tree-lua.txt

@@ -187,12 +187,24 @@ Subsequent calls to setup will replace the previous configuration.
         number = false,
         relativenumber = false,
         signcolumn = "yes",
+        -- @deprecated
         mappings = {
           custom_only = false,
           list = {
             -- user mappings go here
           },
         },
+        float = {
+          enable = false,
+          open_win_config = {
+            relative = "editor",
+            border = "rounded",
+            width = 30,
+            height = 30,
+            row = 1,
+            col = 1,
+          },
+        },
       },
       renderer = {
         add_trailing = false,
@@ -639,6 +651,25 @@ Window / buffer setup.
           Type: `table`
           Default: see |nvim-tree-default-mappings|
 
+    *nvim-tree.view.float*
+    Configuration options for floating window
+
+        *nvim-tree.view.float.enable*
+        Display nvim-tree window as float (enforces |nvim-tree.actions.open_file.quit_on_open| if set).
+          Type: `boolean`, Default: `false`
+
+        *nvim-tree.view.float.open_win_config*
+        Floating window config. See |nvim_open_win| for more details.
+          Type: `table`, Default:
+            `{`
+              `relative = "editor",`
+              `border = "rounded",`
+              `width = 30,`
+              `height = 30,`
+              `row = 1,`
+              `col = 1,`
+            `}`
+
 *nvim-tree.renderer*
 UI rendering setup