chore: per template opt into cached terraform directories (#20609)

For experimental and dogfood purposes, this adds the ability to opt in a single template. 
Leaving the rest of the templates as is. 

For GA, this setting might be removed or changed.

coderd/database/models.go

@@ -4294,6 +4294,7 @@ type Template struct {
 	MaxPortSharingLevel           AppSharingLevel `db:"max_port_sharing_level" json:"max_port_sharing_level"`
 	UseClassicParameterFlow       bool            `db:"use_classic_parameter_flow" json:"use_classic_parameter_flow"`
 	CorsBehavior                  CorsBehavior    `db:"cors_behavior" json:"cors_behavior"`
+	UseTerraformWorkspaceCache    bool            `db:"use_terraform_workspace_cache" json:"use_terraform_workspace_cache"`
 	CreatedByAvatarURL            string          `db:"created_by_avatar_url" json:"created_by_avatar_url"`
 	CreatedByUsername             string          `db:"created_by_username" json:"created_by_username"`
 	CreatedByName                 string          `db:"created_by_name" json:"created_by_name"`
@@ -4343,6 +4344,8 @@ type TemplateTable struct {
 	// Determines whether to default to the dynamic parameter creation flow for this template or continue using the legacy classic parameter creation flow.This is a template wide setting, the template admin can revert to the classic flow if there are any issues. An escape hatch is required, as workspace creation is a core workflow and cannot break. This column will be removed when the dynamic parameter creation flow is stable.
 	UseClassicParameterFlow bool         `db:"use_classic_parameter_flow" json:"use_classic_parameter_flow"`
 	CorsBehavior            CorsBehavior `db:"cors_behavior" json:"cors_behavior"`
+	// Determines whether to keep terraform directories cached between runs for workspaces created from this template. When enabled, this can significantly speed up the `terraform init` step at the cost of increased disk usage. This is an opt-in experience, as it prevents modules from being updated, and therefore is a behavioral difference from the default.
+	UseTerraformWorkspaceCache bool `db:"use_terraform_workspace_cache" json:"use_terraform_workspace_cache"`
 }
 
 // Records aggregated usage statistics for templates/users. All usage is rounded up to the nearest minute.