pgAdmin 4 commit: Improvised the file manager functionalities as per co

Improvised the file manager functionalities as per comments given:
* Do not show the drives on windows, if STORAGE_DIR is set.
* Do not show non-applicable buttons, whenever no files/directory
  present in the storage directory.
* Showing dimmer under the warning messages for replace/delete.
* Select file type other than 'All Files' in create/replace mode.

Tweaked a bit by Ashesh.

Branch
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master

Details
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http://git.postgresql.org/gitweb?p=pgadmin4.git;a=commitdiff;h=5348f6e96a0ef538b991d4e13779847fe67c2384
Author: Surinder Kumar <surinder.kumar@enterprisedb.com>

Modified Files
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web/pgadmin/misc/file_manager/__init__.py          |  68 +++---
.../misc/file_manager/static/css/file_manager.css  |  43 +++-
.../file_manager/templates/file_manager/index.html |  11 +-
.../templates/file_manager/js/file_manager.js      |   6 +-
.../file_manager/js/file_manager_config.json       |  46 ++---
.../templates/file_manager/js/languages/en.js      |   3 +-
.../templates/file_manager/js/utility.js           | 229 +++++++++++++--------
7 files changed, 250 insertions(+), 156 deletions(-)