Dataflow Flex Templates - allow usage of launch options

[bvolpato]

Allow passing launch_options when using Terraform to manage Flex Templates, to allow customizing specific things such as ft_vm_source_image and ft_launch_timeout_secs when required by the customer.

Release Note Template for Downstream PRs (will be copied)

Add optional launch_options to dataflow_flex_template_job

[modular-magician]

Hello! I am a robot. It looks like you are a: ~Community Contributor~ Googler ~Core Contributor~. Tests will run automatically.

@slevenick, a repository maintainer, has been assigned to review your changes. If you have not received review feedback within 2 business days, please leave a comment on this PR asking them to take a look.

You can help make sure that review is quick by doing a self-review and by running impacted tests locally.

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR generated some diffs in downstreams - here they are.

Terraform Beta: Diff ( 3 files changed, 103 insertions(+))

[modular-magician]

Tests analytics

Total tests: 24 Passed tests 0 Skipped tests: 24 Affected tests: 0

Click here to see the affected service packages

• dataflow

$\textcolor{green}{\textsf{All tests passed in REPLAYING mode.}}$ View the build log

[brodin]

Looking forward to this one 👯