Improve success rate for New-ApplicationSubmission

[HowardWolosky]

Migrate New-ApplicationSubmission to use isMinimalResponse
The Store API recently introduced a new option when cloning a new
Application submission (but not for IAP or Flight submissions):
isMinimalResponse=true

When provided, the returned submission object will be shallow (missing
application packages and listings). To get the full submission object,
you need to grab the id from that returned submission object and then
do a GET on that submission.

The benefit of doing this is reducing the likelihood that the API will
time out while trying to put together the newly cloned submission object
to return to us. What has been happening is that when trying to clone
larger submissions, the service will return back a 500 error after it
has successfully cloned, but before it can return back the newly cloned
object.

Fix conflicting access token caching mechanisms
Start-SubmissionMonitor first added access-token caching logic to
limit the need for getting a new access token to just once per 58 minutes.

As of commit 35a9538, Get-AccessToken intelligently returns a cached
access token, only attempting to refresh it when it's about to expire.

Unfortunately, when paired together, an issue was introduced which meant that
Start-SubmissionMonitor might think that the cached access token that it
got back had a 60 minute expiration time (and assumed 58 minutes in order
to have some additional buffer), but in reality, that access token might have
already been cached for 57 minutes.

Due to the double-caching logic, Start-SubmissionMonitor wouldn't attempt to
get a new access token until 58 minutes had passed, but by then the cached token
from Get-AccessToken may have already expired.

The fix here is to just let Get-AccessToken be the sole responsible entity for
caching tokens. There's no reason to provide a "shared" access token to all
commands within Start-SubmissionMonitor for the same reason. We'll just each
individual command try to acquire an AccessToken, letting Get-AccessToken do the
right thing in each instance.

Fix Format-ApplicationSubmission check for trailers
In the past, a submission object with no trailers had a null value
for the trailers node. Now it appears that it returns back an empty
array instead. Checkout $trailers.Count -gt 0 handles both scenarios,
as $null.Count -eq 0 is $true by default.

Resolves #122 Support isMinimalResponse when creating a new submission to reduce the load in the store backend

[danbelcher-MSFT]

My one concern with using this, is that it's not listed in the docs: https://docs.microsoft.com/en-us/windows/uwp/monetize/create-an-app-submission

[HowardWolosky]

I'll follow-up with them to see if they're planning to update MSDN with this parameter. They've specifically asked me to adopt this change however, so I'm not too concerned about adopting it without an MSDN update.

[danbelcher-MSFT]

Is this not available for Flights and Iap?

[HowardWolosky]

Correct. They indicated that getting it working for flights and IAP's would be quite a bit more work.