add new command: git-bump
this command allows to create a commit when bumping a submodule, while creating a nice template for the commit message
initially designed for bumping VTK into paraview
example on my paraview master of $ git bump VTK origin/master
VTK: <SHORT REASON FOR THIS BUMP>
<LONG REASON FOR THIS BUMP>
* Mathieu Westphal: 'vtk parallel vtkPolyDataToImageStencil'
* cbf3814833 Parallelize vtkPolyDataToImageStencil; process slices in parallel.
* Merge-request: https://gitlab.kitware.com/vtk/vtk/merge_requests/9638
* Ben Boeckel: 'ioss symbol exports'
* 4854c6668e ioss: hide symbols properly now
* ee3aa8ba5e vtkCompilerWarningFlags: ignore undefined func templates
* 13501b817c Merge branch 'upstream-ioss' into ioss-symbol-exports
* 9ed8416ef1 ioss 2022-10-20 (19c19a67)
* 7eca930815 ioss: update to 2022-10-14 to export symbols
* f50be34d6e Merge branch 'upstream-fmt' into ioss-symbol-exports
* af3041a03c fmt 2022-10-20 (6406a950)
* 8493b4e946 fmt: update to 9.1.0
* Merge-request: https://gitlab.kitware.com/vtk/vtk/merge_requests/9639
* Aron Helser: 'fix tidy suspicious cxx include'
* b7ce2dc9fd Fix tidy warning `bugprone-suspicious-include`
* Merge-request: https://gitlab.kitware.com/vtk/vtk/merge_requests/9647
* Aron Helser: 'disable extract voi warnings'
* 43976a1214 Convert extract VOI input warnings to debug output.
* Merge-request: https://gitlab.kitware.com/vtk/vtk/merge_requests/9644
Edited by Timothee Chabat