Save Session - Convert file chooser to the operating system's Native File Chooser

Issue is related to IGBF-1140.
Changed Save Session Dialog Style to OS Native File Chooser using FileChooser Utils.
I have tested this on Windows machine. It saves session in valid format and user can open this saved session using Load Session option.

This fix is not supposed to change Window style for Mac because we have different file dialog code for Mac machines.
If we have to change that window as well, then different issue should be created for that.

I am changing the title of this story and some of the description because there is not a "Choose Local Folder" option for this feature, that only applies to stories IGBF-1140 and IGBF-1157. I am doing this to avoid confusion in the future.

Fix the error and tested in Windows.
Need testing in Linux. Fix does not affect Mac Users as we already have Native OS file chooser for MacOS.
Please find committed fix at:
https://bitbucket.org/ashwiniK27/integrated-genome-browser/commits/2e9ea21b2dbd52288939cb406354e969e4e661f8?at=IGBF-1151

1st level review -1

Fix works in Linux, fixed code is searchable and readable. Uploaded a screen shot.

1st level review -2

On mac, no noticeable change, as expected. IGB is able to save a load a session as it should.

I'm reassigning to Ashwini to do a pull request.

After testing this story I can confirm that the Save Session file chooser within has been changed to the operating system's native file chooser. This has been tested on Mac and Windows and is functioning as expected. Saved Sessions are being opened properly in IGB and there seem to be no side effects resulting from this change. Since this issue is resolved it will now be closed.