add deletion_protection field for bigtable instance

[danawillow]

I called it allow_destroy to align with prevent_destroy and terraform destroy, but feel free to suggest a different name if you'd like.

I'm not considering this a breaking change because it doesn't affect users until they want to make a change, but let me know if you disagree.

Once this is merged, I'll follow up with the other bigtable resources.

EDIT: it's called deletion_protection now to align with the field in compute instance.

Release Note Template for Downstream PRs (will be copied)

* bigtable: added `deletion_protection` field to `google_bigtable_instance` to make deleting them require an explicit intent.

* `google_bigtable_instance` resources now cannot be destroyed unless `deletion_protection = false` is set in state for the resource.

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 9 files changed, 104 insertions(+), 11 deletions(-))
Terraform Beta: Diff ( 9 files changed, 104 insertions(+), 11 deletions(-))
TF OiCS: Diff ( 2 files changed, 4 insertions(+))

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 9 files changed, 104 insertions(+), 11 deletions(-))
Terraform Beta: Diff ( 9 files changed, 104 insertions(+), 11 deletions(-))
TF OiCS: Diff ( 2 files changed, 4 insertions(+))

[danawillow]

+riley for oics stuff

[rileykarson]

OiCS changes lgtm- leaving clicking the approval button to @megan07

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 10 files changed, 196 insertions(+), 13 deletions(-))
Terraform Beta: Diff ( 10 files changed, 196 insertions(+), 13 deletions(-))
TF OiCS: Diff ( 2 files changed, 4 insertions(+))

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 10 files changed, 196 insertions(+), 13 deletions(-))
Terraform Beta: Diff ( 10 files changed, 196 insertions(+), 13 deletions(-))
TF OiCS: Diff ( 2 files changed, 4 insertions(+))

[megan07]

LGTM!

[modular-magician]

Hi! I'm the modular magician. Your PR generated some diffs in downstreams - here they are.

Diff report:

Terraform GA: Diff ( 10 files changed, 196 insertions(+), 13 deletions(-))
Terraform Beta: Diff ( 10 files changed, 196 insertions(+), 13 deletions(-))
TF OiCS: Diff ( 2 files changed, 4 insertions(+))