feat(oidc): OIDC Prompt Support (#519)

* feat(oidc): OIDC Prompt Support

Boundary OIDC method does not currently support passing in prompts during authentication. This change adds the capability of passing OIDC prompts. Prompts are optional OIDC parameters that determine the behaviour of the authentication server: https://openid.net/specs/openid-connect-core-1_0.html#AuthRequest

Add new optional `prompts` option to `boundary_auth_method_oidc` resource. `prompts` option are optional OIDC parameters that determine the behavior of the authentication server.

examples/resources/boundary_auth_method_oidc/resource.tf

@@ -16,3 +16,27 @@ resource "boundary_auth_method_oidc" "vault" {
   signing_algorithms = ["RS256"]
   type               = "oidc"
 }
+
+resource "boundary_auth_method_oidc" "oidc_with_one_prompt" {
+  api_url_prefix     = "https://XO-XO-XO-XO-XOXOXO.boundary.hashicorp.cloud:9200"
+  client_id          = "eieio"
+  client_secret      = "hvo_secret_XO"
+  description        = "My Boundary OIDC Auth Method With Prompt"
+  issuer             = "https://sts.windows.net/TENANT_ID/"
+  scope_id           = "global"
+  signing_algorithms = ["RS256"]
+  prompts            = ["select_account"]
+  type               = "oidc"
+}
+
+resource "boundary_auth_method_oidc" "oidc_with_multiple_prompts" {
+  api_url_prefix     = "https://XO-XO-XO-XO-XOXOXO.boundary.hashicorp.cloud:9200"
+  client_id          = "eieio"
+  client_secret      = "hvo_secret_XO"
+  description        = "My Boundary OIDC Auth Method With Multiple Prompts"
+  issuer             = "https://sts.windows.net/TENANT_ID/"
+  scope_id           = "global"
+  signing_algorithms = ["RS256"]
+  prompts            = ["consent", "select_account"]
+  type               = "oidc"
+}