Add window based SLI

[emilymye]

Release Note Template for Downstream PRs (will be copied)

monitoring: Added window-based SLI to `google_monitoring_slo`

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 4 files changed, 2363 insertions(+), 178 deletions(-))
Terraform Beta: Diff ( 4 files changed, 2363 insertions(+), 178 deletions(-))
TF Conversion: Diff ( 1 file changed, 440 insertions(+))
TF OiCS: Diff ( 16 files changed, 509 insertions(+))

[danawillow]

It's going to be a bit weird on the docs since there are a few nested object types that appear multiple times ("the 'X' block supports") but I don't know that there's anything we can really do about it, so I'm fine.

[danawillow]

Suggested change

	# NOTE: If adding properties to requestBasedSli, remember to add to the
	# NOTE: If adding properties to windowsBasedSli, remember to add to the

[modular-magician]

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

Diff report:

Terraform GA: Diff ( 4 files changed, 2363 insertions(+), 178 deletions(-))
Terraform Beta: Diff ( 4 files changed, 2363 insertions(+), 178 deletions(-))
TF Conversion: Diff ( 1 file changed, 440 insertions(+))
TF OiCS: Diff ( 16 files changed, 509 insertions(+))