feat: implement pause and unpause functionality for shipment contract (#99)

[Osuochasam]

I worked on #99
Where i Implemented pause/unpause emergency mechanism

I have run make pre-commit and all checks pass

I have reviewed my own code

I have added comments where necessary, especially in complex sections

I have updated the documentation where required

My changes do not introduce new warnings

I have added tests to validate my changes (if applicable)

All new and existing tests pass locally

Any dependent changes have already been merged

Closes #99

[dinahmaccodes]

Your changes are failing
Ensure your lint and tests are working then push the updated changes

[dinahmaccodes]

also please add the Closes # tag

[dinahmaccodes]

Please resolve conflicts

[Osuochasam]

i have resolved the conflicts
an also added a closing tag

[dinahmaccodes]

update the code please. CI is failing.
And no the close tag wasn't done properly. Let me update it for you

[dinahmaccodes]

@Osuochasam

[dinahmaccodes]

please resolve conflicts and ensure CI passes
lint, fmt and builld
So I can merge your PR