fslrobustfov with padding inorder to remove neck regions in the fsl-bet skull stripped image

Fixes #1928

Fixes #1928 by @birajstha

Description

This PR further expands the work of former cpac developer @tergeorge, by addressing the bug on implementation of RobustFOV. RobustFOV crops the Nifti Image and hence when BET generates the mask, the mask doesnot match the dimension of the original resampled image thus giving error in "3Dcalc" down the pipeline.

Tests

Tested on few (4-5) sample datasets with and without neck regions in the image where it performed as expected.

Checklist

[x] My pull request has a descriptive title (not a vague title like Update index.md).
[x] My pull request targets the add_fslrobustfov branch of the repository.
[x] My commit messages follow best practices.
[x] My code follows the established code style of the repository.
[ ] I added tests for the changes I made (if applicable).
[ ] I updated the changelog.
[ ] I added or updated documentation (if applicable).
[x] I tried running the project locally and verified that there are no visible errors.

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FCP-INDI / C-PAC