xWebSite: skip certificate thumbprint and store name check when SslFlags are valid

[changbowen]

Pull Request (PR) description

SslFlags value 2 and 3 suggest the use of CCS (Central Certificate Store). Checking for certificate thumbprint and store name should be skipped when CCS is being used.

In IIS Management Console the SSL certificate field would be disabled when CCS is enabled.

This Pull Request (PR) fixes the following issues

Fixes #199

Task list

• Added an entry to the change log under the Unreleased section of the
  file CHANGELOG.md. Entry should say what was changed and how that
  affects users (if applicable), and reference the issue being resolved
  (if applicable).
• Resource documentation added/updated in README.md.
• Resource parameter descriptions added/updated in README.md, schema.mof
  and comment-based help.
• Comment-based help added/updated.
• Localization strings added/updated in all localization files as appropriate.
• Examples appropriately added/updated.
• Unit tests added/updated. See DSC Community Testing Guidelines.
• Integration tests added/updated (where possible). See DSC Community Testing Guidelines.
• New/changed code adheres to DSC Community Style Guidelines.

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This change is 

[johlju]

Reviewed all commit messages.
Reviewable status: 0 of 1 files reviewed, 3 unresolved discussions (waiting on @changbowen and @johlju)

a discussion (no related file):
Please add a unit test for this change: https://github.com/dsccommunity/xWebAdministration/blob/673d20f7a73d2e6bfdd0715a5628bd7ffa708d5f/tests/Unit/MSFT_xWebsite.Tests.ps1#L2273

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a discussion (no related file):
Please update the CHANGELOG.md with an entry for this change.

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source/DSCResources/MSFT_xWebSite/MSFT_xWebSite.psm1, line 1439 at r1 (raw file):

                {
                    if ([Environment]::OSVersion.Version -lt '6.2' -or $binding.SslFlags -notin @('2', '3'))
                    {

We should indent the code inside the brace.

[changbowen]

Indent added.
Sorry I'm not really familiar with the workflow.. had a hard time understanding the unit tests.. Am I supposed to make changes to the unit test and change log files?

[johlju]

Yes to both. You should add a unit test that verifies that the new code path works, and if existing tests fail then either the code change must be revised or existing unit tests revised.

The CHANGELOG.md is used as the release notes for the next release. By adding a new entry under the Unreleased-section it will be automatically used in the release notes.

[johlju]

We have renamed the resource, removeing 'x', so please rebase this PR.

[david-garcia-garcia]

Works if you use: CertificateThumbprint = 'Allow'