feat(makefile): add targets to install and remove CA cert on local PC

- Add install-ca and remove-ca targets to GNUmakefile.

- Allows local installation/removal of certs/koji_ca_cert.crt into the system CA trust anchors.

Co-developed-by: Gemini AI <renich+gemini@woralelandia.com>

Signed-off-by: Rénich Bon Ćirić <renich@woralelandia.com>

roles/koji_hub/files/koji-sign-spooler

@@ -27,6 +27,7 @@ def get_siguldry_key_info():
     """
     env = os.environ.copy()
     env['SIGULDRY_SOCKET'] = '/run/siguldry-client-proxy/siguldry-client-proxy.socket'
+    env['CREDENTIALS_DIRECTORY'] = '/etc/credstore'
     
     # Get key info
     res = subprocess.run(
@@ -199,6 +200,7 @@ def process_queue():
                 env = os.environ.copy()
                 env['PKCS11_MODULE_PATH'] = '/usr/lib64/pkcs11/libsiguldry_pkcs11.so'
                 env['SIGULDRY_SOCKET'] = '/run/siguldry-client-proxy/siguldry-client-proxy.socket'
+                env['CREDENTIALS_DIRECTORY'] = '/etc/credstore'
 
                 # Sign using rpmsign command with Sequoia backend macro definitions
                 cmd = [