bazel: `@envoy_api` should not depend on `@envoy` (#34759)

The extra dependency was introduced in 65273b2a9b. pgv.patch is only
used by envoy_api, so just moving the file avoids the dependency.

Signed-off-by: Eric Anderson <ejona@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ 9fde867399cc7fcf97815995f8466f62172b26f6

bazel/pgv.patch

@@ -0,0 +1,13 @@
+--- a/templates/cc/register.go	2023-06-22 14:25:05.776175085 +0000
++++ b/templates/cc/register.go	2023-06-22 14:26:33.008090583 +0000
+@@ -116,6 +116,10 @@
+ func (fns CCFuncs) methodName(name interface{}) string {
+ 	nameStr := fmt.Sprintf("%s", name)
+ 	switch nameStr {
++	case "concept":
++		return "concept_"
++	case "requires":
++		return "requires_"
+ 	case "const":
+ 		return "const_"
+ 	case "inline":

bazel/repositories.bzl

@@ -19,7 +19,7 @@ def api_dependencies():
     external_http_archive(
         name = "com_envoyproxy_protoc_gen_validate",
         patch_args = ["-p1"],
-        patches = ["@envoy//bazel:pgv.patch"],
+        patches = ["@envoy_api//bazel:pgv.patch"],
     )
     external_http_archive(
         name = "com_google_googleapis",