Fix UI freezing while searching for users

[tsekityam]

Too many suggestions may freeze the UI. Limiting the number of suggestions show to user reduces the chances of freezing.

Q	A
Bug fix?	[x]
New feature?	[ ]
New sample?	[ ]
Related issues?	mentioned in #143

What's in this Pull Request?

People picker may be freezing if there are too many matchings, such as searching for users that match a in a tenet with thousands of users.

This patch introduces a new property suggestionLimit to limit the max number of suggestions show to user.

[codecov-io]

Codecov Report

Merging #145 into dev will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev     #145   +/-   ##
=======================================
  Coverage   80.63%   80.63%           
=======================================
  Files          10       10           
  Lines         346      346           
  Branches       78       78           
=======================================
  Hits          279      279           
  Misses         44       44           
  Partials       23       23

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