m.nviz.image: Fix Resource Leak issue

[ShubhamDesai]

This pull request fixes issue identified by Coverity Scan (CID : 1207735, 1207736, 1207924, 1207925, 1208025, 1208026, 1208027, 1208028, 1208029, 1400466, 1501205, 1501280, 1501338)
Used G_free() to fix this issue.

[nilason]

There are a number of similar issues in m.nviz.image, please filter with misc/m.nviz.image/*, to address them all (they all seem to be uncomplicated).

[ShubhamDesai]

There are a number of similar issues in m.nviz.image, please filter with misc/m.nviz.image/*, to address them all (they all seem to be uncomplicated).

done all changes

[nilason]

All calls to G_fully_qualified_name() returns an allocated value which must be freed.

[ShubhamDesai]

All calls to G_fully_qualified_name() returns an allocated value which must be freed.

done

[ShubhamDesai]

All calls to G_fully_qualified_name() returns an allocated value which must be freed.

is there anything wrong in code? mac build failed.
I would fix the clang formatting issues sorry about the noise.

[nilason]

I added a few suggestions.

[nilason]

Just a minor suggestion, otherwise good!