Support for cross-project secrets for GCP

[jeevb]

TL;DR

Adds support for cross-project secrets on GCP. Tested with the following examples:

Cross-project example:

from flytekit import Secret, current_context, task

SECRET_GROUP = "projects/111111111111/secrets/mainsecret"
SECRET_GROUP_VERSION = "1"


@task(
    secret_requests=[
        Secret(group=SECRET_GROUP, group_version=SECRET_GROUP_VERSION),
    ],
)
def my_task() -> str:
    return current_context().secrets.get(
        SECRET_GROUP, group_version=SECRET_GROUP_VERSION
    )

Backward compatibility with secrets in current project:

from flytekit import Secret, current_context, task

SECRET_GROUP = "mainsecret"
SECRET_GROUP_VERSION = "1"


@task(
    secret_requests=[
        Secret(group=SECRET_GROUP, group_version=SECRET_GROUP_VERSION),
    ],
)
def my_task() -> str:
    return current_context().secrets.get(
        SECRET_GROUP, group_version=SECRET_GROUP_VERSION
    )

Type

• Bug Fix
• Feature
• Plugin

Are all requirements met?

• Code completed
• Smoke tested
• Unit tests added
• Code documentation added
• Any pending items have an associated Issue

Complete description

How did you fix the bug, make the feature etc. Link to any design docs etc

Tracking Issue

Remove the 'fixes' keyword if there will be multiple PRs to fix the linked issue

fixes https://github.com/flyteorg/flyte/issues/

Follow-up issue

NA
OR
https://github.com/flyteorg/flyte/issues/

[wild-endeavor]

why do we want to support cross project secrets?

[jeevb]

why do we want to support cross project secrets?

Parity with AWS that already supports cross-account secrets via ARNs.

[codecov]

Codecov Report

Merging #582 (76691ae) into master (d181df7) will increase coverage by 0.38%.
The diff coverage is 100.00%.

❗ Current head 76691ae differs from pull request most recent head 106fb2c. Consider uploading reports for the commit 106fb2c to get more accurate results