share: introduce config option to store requires in .hg/store This introduces a config option which enabled stores the requirements on a repository in store instead. When enabled, `.hg/requires` will contain the `share-safe` requirement which marks that the requirements are present in the store. This is done so that repository requirements can be shared with shares made using `hg share` command. After this patch, `hg share` checks whether the source repository has share-safe requirement, if yes, it does not copy the requirements. Test for the new functionality is added and a test case in exitsing share tests is also added. Differential Revision: https://phab.mercurial-scm.org/D8633