fix tgc imports (#15595)

Author: zli82016

mmv1/templates/tgc_next/cai2hcl/resource_converter.go.tmpl

@@ -19,6 +19,7 @@ package {{ lower $.ProductMetadata.Name }}
 import (
 	"fmt"
 	"reflect"
+	"regexp"
 	"strings"
 
 {{/* We list all the v2 imports here and unstable imports, because we run 'goimports' to guess the correct

mmv1/templates/tgc_next/tfplan2cai/resource_converter.go.tmpl

@@ -17,6 +17,7 @@
 package {{ lower $.ProductMetadata.Name }}
 
 import (
+  "encoding/base64"
   "fmt"
   "log"
   "reflect"
@@ -46,6 +47,7 @@ import (
 )
 
 var (
+    _ = base64.StdEncoding
     _ = fmt.Sprintf
     _ = log.Print
     _ = reflect.ValueOf