Allow specifying environment variables for Terraform commands

[nghialv]

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #2770

Does this PR introduce a user-facing change?:

NONE

[pipecd-bot]

Code coverage for golang is 32.09%. This pull request decreases coverage by -0.04%.

File	Function	Base	Head	Diff
pkg/app/piped/cloudprovider/terraform/terraform.go	WithAdditionalEnvs	--	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Apply	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Version	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Init	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.SelectWorkspace	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Plan	0.00%	0.00%	+0.00%

[pipecd-bot]

The golinter build is completed with FAILURE. The build will be triggered again when you push any other commits. Or you can trigger it manually by /golinter trigger command right now.

You can check the build log from here.

[pipecd-bot]

Code coverage for golang is 32.09%. This pull request decreases coverage by -0.04%.

File	Function	Base	Head	Diff
pkg/app/piped/cloudprovider/terraform/terraform.go	WithAdditionalEnvs	--	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Version	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Init	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.SelectWorkspace	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Plan	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Apply	0.00%	0.00%	+0.00%

[pipecd-bot]

Code coverage for golang is 32.09%. This pull request decreases coverage by -0.04%.

File	Function	Base	Head	Diff
pkg/app/piped/cloudprovider/terraform/terraform.go	WithAdditionalEnvs	--	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Init	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.SelectWorkspace	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Plan	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Apply	0.00%	0.00%	+0.00%
pkg/app/piped/cloudprovider/terraform/terraform.go	Terraform.Version	0.00%	0.00%	+0.00%

[ono-max]

Nice.

/lgtm

[nakabonne]

I'm sure it will work as well as we'd like 👍
/approve

[pipecd-bot]

This pull request is APPROVED by nakabonne.

Approvers can cancel the approval by writing /approve cancel in a comment. Any additional commits also will change this pull request to be not-approved.