SqlDatabasePermission: Supports roles and application roles

[johlju]

Pull Request (PR) description

• SqlDatabasePermission
  • Now possible to change permissions for database user-defined roles
    (e.g. public) and database application roles (issue SqlDatabasePermission: Cannot grant or revoke permissions from database role #1498).

This Pull Request (PR) fixes the following issues

• Fixes SqlDatabasePermission: Cannot grant or revoke permissions from database role #1498

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 

[codecov]

Codecov Report

Merging #1558 into master will increase coverage by 0%.
The diff coverage is 100%.

@@          Coverage Diff           @@
##           master   #1558   +/-   ##
======================================
  Coverage      98%     98%           
======================================
  Files          36      36           
  Lines        5847    5850    +3     
======================================
+ Hits         5738    5741    +3     
  Misses        109     109           

[johlju]

Reviewed 3 of 4 files at r1, 1 of 1 files at r2, 1 of 1 files at r3.
Reviewable status: complete! all files reviewed, all discussions resolved