Add the privateca certificate template resource.

[modular-magician]

• update serialization code so that the sample test can be autogenerated.
• fix minor issues in samples generation code (underscores vs title vase)
• add privateca to provider
• add ability to expand and flatten int arrays.
• remove cloud run serialization (and relevant tests) since it no longer exists in the DCL.

Fixes #9607

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`google_privateca_certificate_template`

Derived from GoogleCloudPlatform/magic-modules#5109

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