Added build flag to allow/skip building Example Credential files (#25953)

Author: sharadb-amazon

src/credentials/BUILD.gn

@@ -17,6 +17,10 @@ import("//build_overrides/nlassert.gni")
 import("${chip_root}/src/crypto/crypto.gni")
 import("${chip_root}/src/platform/device.gni")
 
+declare_args() {
+  chip_build_example_creds = true
+}
+
 static_library("credentials") {
   output_name = "libCredentials"
 
@@ -47,16 +51,21 @@ static_library("credentials") {
     "attestation_verifier/DeviceAttestationDelegate.h",
     "attestation_verifier/DeviceAttestationVerifier.cpp",
     "attestation_verifier/DeviceAttestationVerifier.h",
-    "examples/DeviceAttestationCredsExample.cpp",
-    "examples/DeviceAttestationCredsExample.h",
-    "examples/ExampleDACs.cpp",
-    "examples/ExampleDACs.h",
-    "examples/ExamplePAI.cpp",
-    "examples/ExamplePAI.h",
-    "examples/LastKnownGoodTimeCertificateValidityPolicyExample.h",
-    "examples/StrictCertificateValidityPolicyExample.h",
   ]
 
+  if (chip_build_example_creds) {
+    sources += [
+      "examples/DeviceAttestationCredsExample.cpp",
+      "examples/DeviceAttestationCredsExample.h",
+      "examples/ExampleDACs.cpp",
+      "examples/ExampleDACs.h",
+      "examples/ExamplePAI.cpp",
+      "examples/ExamplePAI.h",
+      "examples/LastKnownGoodTimeCertificateValidityPolicyExample.h",
+      "examples/StrictCertificateValidityPolicyExample.h",
+    ]
+  }
+
   # TODO: These tests files should be removed after the DeviceAttestationCredsExample implementation
   # is changed to generate it's own credentials instead of using Test credentials.
   # For some platforms test builds, which are bilding monolithic test library these files are not needed.