[IgxSimpleCombo]: clear input on blur when combo is collapsed - master

[RivaIvanova]

Closes #12100

This PR also fixes an issue where the closing event was emitted once when closing the combo via the toggle button, but twice when closing it when clicking outside of it.

NOTE FOR TESTING :

• Verify that the input is cleared when closing the combo via the toggle button and immediately clicking outside of the combo, i.e., the below should not be reproducible:

Additional information (check all that apply):

• Bug fix
• New functionality
• Documentation
• Demos
• CI/CD

Checklist:

• All relevant tags have been applied to this PR
• This PR includes unit tests covering all the new code (test guidelines)
• This PR includes API docs for newly added methods/properties (api docs guidelines)
• This PR includes feature/README.MD updates for the feature docs
• This PR includes general feature table updates in the root README.MD
• This PR includes CHANGELOG.MD updates for newly added functionality
• This PR contains breaking changes
• This PR includes ng update migrations for the breaking changes (migrations guidelines)
• This PR includes behavioral changes and the feature specification has been updated with them