* fix duplicated slash in s:Path.isUnder() (on windows OS) (#1122)

* * fix duplicated slash in s:Path.isUnder() (on windows OS, for root directory on drive Path.str() return path with [back]slash)

* * Rewrite NERDTreePath.isUnder() and NERDTreePath.isAncestor() for direct comparison of paths without transformations

* Remove trailing slash, so we don't end up with two on root folder.

The str() function returns "C:\" on the root folder and "C:\temp" on
non-root folders, one with and one without a trailing backslash. This
inconsistency needs to be handled so the stridx() function will work
correctly.

* Make sure the change also works in a non-windows file system.

This commit handles an edge case that can be triggered with these
commands:
    :cd /home/me
    :e /foobar.txt  (an existing file)
    :NERDTreeFind
What happened was the root directory name '/' was being Resolved(), and
the trailing (and only) slash was being removed. The NERDTree was then
created in the current working directory, instead of the root directory.
:NERDTreeFind then wasn't able to find foobar.txt, and printed an error.

* Remove degugging statements.

* * ambiguity issue fix

Co-authored-by: Phil Runninger <philrunninger@gmail.com>

CHANGELOG.md

@@ -5,6 +5,7 @@
         - **.PATCH**: Pull Request Title (PR Author) [PR Number](Link to PR)
 -->
 #### 6.7
+- **.11**: Fix exception in NERDTreeFind (on windows OS and If the file is located in the root directory of the disk)  [#1122](https://github.com/preservim/nerdtree/pull/1122)
 - **.10**: Do not consider the tree root to be "cascadable". (lifecrisis) [#1120](https://github.com/preservim/nerdtree/pull/1120)
 - **.9**: Force `:NERDTreeFocus` to allow events to be fired when switching windows. (PhilRunninger) [#1118](https://github.com/preservim/nerdtree/pull/1118)
 - **.8**: Fix example code for the `NERDTreeAddKeyMap()` function. (PhilRunninger) [#1116](https://github.com/preservim/nerdtree/pull/1116)