fix(gui): SSL public key hint must have a certificate file extension (#…

…854)

Thanks @edibotopic for noticing that :)

Additional to that fix. the first commit of this PR moves a user-facing
string (SSL Key input label) from the source code to the translatable
resource, so it can be properly localized.

gui/packages/ubuntupro/lib/l10n/app_en.arb

@@ -72,6 +72,7 @@
     "landscapeKeyLabel": "Registration Key",
     "landscapeCustomSetup": "Advanced Configuration",
     "landscapeCustomSetupHint": "Load a custom Landscape client configuration file",
+    "landscapeSSLKeyLabel": "Server SSL public key",
     "landscapeFileLabel": "Config file path",
     "landscapeFileTooLarge": "Configuration file is too large",
     "landscapeFileEmptyPath": "A path must be specified",

gui/packages/ubuntupro/lib/pages/landscape/landscape_page.dart

@@ -378,8 +378,8 @@ class _SelfHostedForm extends StatelessWidget {
           child: _FilePickerField(
             buttonLabel: lang.landscapeFilePicker,
             errorText: model.selfHosted.fileError.localize(lang),
-            hint: 'C:\\landscape.conf',
-            inputlabel: 'Server SSL public key',
+            hint: 'C:\\landscape.pem',
+            inputlabel: lang.landscapeSSLKeyLabel,
             onChanged: model.setSslKeyPath,
           ),
         ),