Updated Swift Autocompletion Syntax

[alexaubry]

Performed updates to the Swift Snippets JSON so that they match the latest language syntax

Updated :

• print()
• repeat {} while

Added :

• Guard statement
• Optional Binding Statement

[msftclas]

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[msftclas]

@alexaubry, Thanks for signing the contribution license agreement so quickly! Actual humans will now validate the agreement and then evaluate the PR.

Thanks, MSBOT;

[aeschli]

Thanks @alexaubry !