chore: implement OIDCClaimFieldValues for idp sync mappings auto complete (#15576)

When creating IDP sync mappings, these are the values that can be
selected from. These are the values that can be mapped from in
org/group/role sync.

coderd/database/queries.sql.go

@@ -9869,6 +9869,67 @@ func (q *sqlQuerier) InsertUserLink(ctx context.Context, arg InsertUserLinkParam
 	return i, err
 }
 
+const oIDCClaimFieldValues = `-- name: OIDCClaimFieldValues :many
+SELECT
+	-- DISTINCT to remove duplicates
+	DISTINCT jsonb_array_elements_text(CASE
+		-- When the type is an array, filter out any non-string elements.
+		-- This is to keep the return type consistent.
+		WHEN jsonb_typeof(claims->'merged_claims'->$1::text) = 'array' THEN
+			(
+				SELECT
+					jsonb_agg(element)
+				FROM
+					jsonb_array_elements(claims->'merged_claims'->$1::text) AS element
+				WHERE
+					-- Filtering out non-string elements
+					jsonb_typeof(element) = 'string'
+			)
+		-- Some IDPs return a single string instead of an array of strings.
+		WHEN jsonb_typeof(claims->'merged_claims'->$1::text) = 'string' THEN
+			jsonb_build_array(claims->'merged_claims'->$1::text)
+	END)
+FROM
+	user_links
+WHERE
+	-- IDP sync only supports string and array (of string) types
+	jsonb_typeof(claims->'merged_claims'->$1::text) = ANY(ARRAY['string', 'array'])
+	AND login_type = 'oidc'
+	AND CASE
+		WHEN $2 :: uuid != '00000000-0000-0000-0000-000000000000'::uuid  THEN
+			user_links.user_id = ANY(SELECT organization_members.user_id FROM organization_members WHERE organization_id = $2)
+		ELSE true
+	END
+`
+
+type OIDCClaimFieldValuesParams struct {
+	ClaimField     string    `db:"claim_field" json:"claim_field"`
+	OrganizationID uuid.UUID `db:"organization_id" json:"organization_id"`
+}
+
+func (q *sqlQuerier) OIDCClaimFieldValues(ctx context.Context, arg OIDCClaimFieldValuesParams) ([]string, error) {
+	rows, err := q.db.QueryContext(ctx, oIDCClaimFieldValues, arg.ClaimField, arg.OrganizationID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []string
+	for rows.Next() {
+		var jsonb_array_elements_text string
+		if err := rows.Scan(&jsonb_array_elements_text); err != nil {
+			return nil, err
+		}
+		items = append(items, jsonb_array_elements_text)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const oIDCClaimFields = `-- name: OIDCClaimFields :many
 SELECT
 	DISTINCT jsonb_object_keys(claims->'merged_claims')