localrepo: support writing shared file (API) Now that we can create a shared repository via creation options, we can handle other special actions related to share at repo creation time as well. One of the things we do after creating a shared repository is write out a .hg/shared file containing the list of additional things to share. Of which only "bookmarks" is supported. We add a creation option to hold the set of additional items to share. If items are defined, we write out the .hg/shared file at repo creation time. As part of this, we no longer hold the repo lock when writing the file. I'm pretty sure we don't care about the tiny race condition window. I'm also pretty sure the reason we used the lock was because the vfs auditor on the repo instance complained otherwise. Since the repo creation code doesn't have an audited vfs, we don't need to appease it. Because we no longer need to tell the post share hook what items are shared, the "bookmarks" argument to that function has been dropped, incurring an API change. Differential Revision: https://phab.mercurial-scm.org/D4708