App supports bazel

[mys007]

What changes are proposed in this pull request?

When fiftyone is installed under bazel environment and fo.launch_app() is called, the App does not launch and only 404 is displayed.

This is because bazel creates virtual package installations, where everything - including fiftyone/server/static - is just a symbolic link to a central, shared location. The story with bazel is also mentioned in encode/starlette#1083 and was one of the motivation for introducing StaticFiles(follow_symlink=True) for this purpose.

This PR turns on the support for symlinks for the static directory, so that fiftyone works with bazel.

How is this patch tested? If it is not, please explain why.

Tested locally.

Release Notes

Is this a user-facing change that should be mentioned in the release notes?

• No. You can skip the rest of this section.
• Yes. Give a description of this change to be included in the release
  notes for FiftyOne users.

(Details in 1-2 sentences. You can just refer to another PR with a description
if this PR is part of a larger change.)

What areas of FiftyOne does this PR affect?

• App: FiftyOne application changes
• Build: Build and test infrastructure changes
• Core: Core fiftyone Python library changes
• Documentation: FiftyOne documentation changes
• Other

[benjaminpkane]

LGTM! Thanks @mys007!

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (5a929eb) 15.48% compared to head (ee2001b) 15.48%.

Additional details and impacted files

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##           develop    #3338   +/-   ##
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  Coverage    15.48%   15.48%           
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  Files          569      569           
  Lines        70351    70351           
  Branches       687      687           
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  Hits         10895    10895           
  Misses       59456    59456           

Flag	Coverage Δ
app	15.48% <ø> (ø)

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