During a refactoring I accidentally omitted the `$manifestPath`
variable that is required to determine the `$manifestDirectory`
for the submission command to WinGet. Since the directory is
just a constant, let's update the submission command.

Signed-off-by: Matthew John Cheetham <mjcheetham@outlook.com>
Signed-off-by: Johannes Schindelin <johasc@microsoft.com>

During a refactoring the `$manifestPath` variable assignment was
accidentally omitted which is required to determine the
`$manifestDirectory` for the submission command to WinGet. Since the
`$manifestDirectory` is just a constant, let's update the submission
command.

Some things seem to have changed in `wingetcreate.exe` so that the
directory structure is different, and the manifest location can no
longer be specified as vaguely as before, therefore this all looks quite
a bit more involved than simply specifying `./manifests` instead of
`$manifestDirectory`.

This change to use the 'info/' directory instead of the 'hooks/'
directory is important because the hooks dir could be redirected to the
source tree.

Modify the test in such a way that this code change would fail due to
being unable to write to the internal hooks directory.

Signed-off-by: Derrick Stolee <stolee@gmail.com>

Before making the post-index-change logic more advanced for the
postCommand.strategy=post-index-change feature, extract the code into a
new method that will be easier to update in the future.

Signed-off-by: Derrick Stolee <stolee@gmail.com>

The postCommand.strategy=post-index-change config was designed to
replace some internal hook usage. This internal hook was more
restrictive than the initial feature was designed. Specifically, it
ignored index updates that did not update the worktree. With the
existing implementation, this causes more work done in the post-command
hook than intended.

Update the code to write a sentinel file only when the worktree is
changed.

Signed-off-by: Derrick Stolee <stolee@gmail.com>

The previously-named 'post-index-change' value for
'postCommand.strategy' did the following two things:

 1. Avoid running the post-command hook unless the post-index-change
    hook _would_ run with a signal that the worktree changed.

 2. Avoid running any installed post-index-change hooks.

The additional restriction of the worktree change in (1) makes this name
less appropriate. Also, item (2) seems to be a side-effect that we
should avoid. We would like to allow both behaviors to exist.

Update the value and behavior, including the tests.

Signed-off-by: Derrick Stolee <stolee@gmail.com>

Now that we don't skip the post-index-change hook, we don't need to pass
the return value as an out-parameter in this method.

Signed-off-by: Derrick Stolee <stolee@gmail.com>

This feature was introduced in #736 but had a few pain points that were
discovered when testing the full replacement of the existing
post-index-change and post-command hooks in our internal environment:

1. When using `core.hooksPath` to point to a directory within the
worktree, the sentinel files were being written into the worktree. Write
to `$GITDIR/info/` instead.
2. The existing internal post-index-change hook only signaled that work
needed to be done if actually the _worktree_ changed. Make the sentinel
file logic more restrictive to only write in these cases.

Tests are added to confirm both of these behavior changes.

To reflect the changed behavior, the name `post-index-change` was renamed
to `worktree-change`.