Merge branch 'tapashree/dmshellsetcreatefielddecomposition' into 'main'

Add Fortran interface for DMShellSetCreateFieldDecomposition

Closes #165

See merge request petsc/petsc!8436

Adds Fortran interface for DMShellSetCreateFieldDecomposition

- Implemented the Fortran interface for the DMShellSetCreateFieldDecomposition function to enable Fortran users to utilize this function

Adds Fortran interface for DMShellSetCreateFieldDecomposition

- Implemented the Fortran interface for the DMShellSetCreateFieldDecomposition function to enable Fortran users to utilize this functionality.This involved adding a new callback field in the callback structure, creating a C wrapper for the Fortran callback, and providing a Fortran-callable function to register the callback.
- Add a simple test to verify the functionality
- Remove unused comments and variables
Fix issue #165.

Add test for DMShellSetCreateFieldDecomposition

Introduce a simple test for DMShellSetCreateFieldDecomposition fortran interface

Set ierr as intent(out) in fortran interface to avoid error

Consistent formatting of files

removed unnecessary comment in zdmshellf.c

TEST block fix for the new test case

remove unused variables in dm/tests/ex54f

remove dm_view unused option from test block

fix interface declaration for myFileDecomp

fix the ierr type errors

fix ierr type error

add newline at end of files

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