[Examples/Tests] Convert @imports to imports

[romoore]

In order to make the internal build systems happier, @import statements should not be used.

[ianegordon]

Let's chat on this tomorrow.

[codecov-io]

Codecov Report

Merging #2761 into develop will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #2761   +/-   ##
========================================
  Coverage    46.89%   46.89%           
========================================
  Files          165      165           
  Lines        24651    24651           
  Branches      1060     1060           
========================================
  Hits         11561    11561           
  Misses       13027    13027           
  Partials        63       63

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[romoore]

This is necessary for both internal builds, but also for bazel builds on kokoro. In order for us to include building our examples (a very good thing) on Kokoro, we'll have to make this change until bazel supports modules imports.

[ianegordon]

Acknowledged. Let's make sure we open an issue with the Bazel team if there isn't one already.