Add PBT to experiment creation form

[a9p]

What this PR does / why we need it:

This PR adds PBT as an option to the search algorithms drop-down for creating a new experiment from the Katib UI.

Related to: #1382, #1862

Checklist:

• [-] Docs included if any changes are user facing

[coveralls]

Coverage increased (+0.1%) to 72.974% when pulling d83cf22 on a9p:pbt-ui-newexp-only into cfa2d84 on kubeflow:master.

[a9p]

cc/ @johnugeorge - this adds minimal functionality to at least expose PBT options through the UI

[kimwnasptd]

@johnugeorge the changes LGTM for the frontend. If you are also OK with the underlying logic and params exposed we should be good with merging this.

Although I'd suggest to first merge #1783, since it's easier to rebase this one later one if we have small conflicts. I'll give a heads up once I wrap the review of #1783.

/lgtm

[johnugeorge]

Sure. We will wait for #1783 to get merged first
/hold

[johnugeorge]

/hold cancel

[johnugeorge]

/approve

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: a9p, johnugeorge

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