[electron] File dialog filters do not work

[kittaakos]

Bug Description:

I found this bug when reviewing #9184. Although a filter is correctly configured:

theia/packages/vsx-registry/src/browser/vsx-extensions-contribution.ts

Lines 164 to 169 in 14df86f

	const props: OpenFileDialogProps = {
	title: VSXExtensionsCommands.INSTALL_FROM_VSIX.dialogLabel,
	openLabel: 'Install',
	filters: { 'VSIX Extensions (*.vsix)': ['vsix'] },
	canSelectMany: false
	};

It has no effect, as we always use the * filter. This code should be changed:

theia/packages/filesystem/src/electron-browser/file-dialog/electron-file-dialog-service.ts

Lines 96 to 99 in edc346b

	const filters: FileFilter[] = [{ name: 'All Files', extensions: ['*'] }];
	if (props.filters) {
	filters.push(...Object.keys(props.filters).map(key => ({ name: key, extensions: props.filters![key] })));
	}

Expected:

diff --git a/packages/filesystem/src/electron-browser/file-dialog/electron-file-dialog-service.ts b/packages/filesystem/src/electron-browser/file-dialog/electron-file-dialog-service.ts
index 10729331d5..eff76250aa 100644
--- a/packages/filesystem/src/electron-browser/file-dialog/electron-file-dialog-service.ts
+++ b/packages/filesystem/src/electron-browser/file-dialog/electron-file-dialog-service.ts
@@ -93,9 +93,11 @@ export class ElectronFileDialogService extends DefaultFileDialogService {
     protected toDialogOptions(uri: URI, props: SaveFileDialogProps | OpenFileDialogProps, dialogTitle: string): electron.FileDialogProps {
         const title = props.title || dialogTitle;
         const defaultPath = FileUri.fsPath(uri);
-        const filters: FileFilter[] = [{ name: 'All Files', extensions: ['*'] }];
+        const filters: FileFilter[] = [];
         if (props.filters) {
             filters.push(...Object.keys(props.filters).map(key => ({ name: key, extensions: props.filters![key] })));
+        } else {
+            filters.push({ name: 'All Files', extensions: ['*'] });
         }
         return { title, defaultPath, filters };
     }

Steps to Reproduce:

Additional Information

• Operating System:
• Theia Version:

[scottaxcell]

@kittaakos this looks like a good first issue to get my feet wet. Can I help with this issue?