Bug fix: Make object revision match datastore revision

[aaandreeew]

Fixes #179.

Upon changes in the vault, the revision of any newly-modified object matches that of the datastore.

I have hand-tested this in a vault with the following datacore block while editing another page in a split view. I compared the results before and after this change.

return function View() {
    const revision = dc.useIndexUpdates();
    const pages = dc.useMemo(
        () => dc.query(`@page and $revision >= ${revision - 1}`),
        [revision]
    );
    
    return <>
        Revision: {revision}
        <dc.List
            rows={pages}
            renderer={page => `${page.$path}: ${page.$revision}`}
        />
    </>
}

PS: Could someone explain the proper way to work with feature branches on a fork when fixing bugs? As you can see, this PR contains two redundant commits relating to my last bugfix. I made my last bugfix on a feature branch that got merged into this repo's main. That merge commit was then pulled into in my fork's main branch as expected. To get rid of that last feature branch, I just merged it into my main and deleted it, since that's what I normally do. But now, since this PR's branch is based on that, those merge commits (not squashed, but that's only part of the issue) are included, even thought they're redundant.