Feature multi select

[ChrisPates]

Issue #, if available:

156, #136, #101, #69, #66, #34, #28

Description of changes:

• now support multiple group prefixes in groupMatch parameter
• supports both group and user match in combination.
  • '*' - matches all
  • '' - do not perform match
  • 'single or multi match patterns' - as defined
• Above feature makes it easier to specify specific groups or users to include.
• nested groups now supported by 'flattening' nesting into the top level group
• external users correctly identified and excluded from syncs
• owner role in groups explicitly ignored as no equivalent exists in IAM Identity Center

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