sui-multi-select: option pills - Keyboard support to navigate and delete

[srikant]

Please read https://github.com/edcarroll/ng2-semantic-ui/blob/master/CONTRIBUTING.md and search
existing issues (both open and closed) prior to opening any new issue and ensure you follow the instructions therein.

Bug description:

I have been observed differences in "ng2-semantic-ui" and "ng2-semantic-ui" multi-select interaction.
No keyboard support to navigate, select, delete 'sui-multi-select' option pills.

Link to minimally-working plunker that reproduces the issue:

• Open ng2-semantic-ui official select example and semantic-ui official dropdown example
• Select multiple options from dropdown
• Not able to navigate between option pills if I press "LEFT" or "RIGHT" arrow keys
• Not able to select all option pills if i press "SHIFT + LEFT" or "SHIFT + RIGHT" keys
• Not able to select and delete any specific option pill using "MOUSE SELECT" + "DELETE" key

Version of Angular, ng2-semantic-ui, and Semantic UI:

Angular: (^6.0.0)

ng2-semantic-ui: (0.10.0-alpha.6)

Semantic UI: (^2.3.1)