Fix text settings to be honored in Canvas markdown elements (#179948)

The `style` could be set in the legacy React `<Markdown>` component, so this change imitates it in the new shared ux markdown as well.

packages/shared-ux/markdown/impl/README.mdx

@@ -11,6 +11,7 @@ date: 2022-10-03
 
 This markdown component uses the **EuiMarkdownEditor** and **EuiMarkdownFormat** managed by `@elastic/eui`. If `readOnly` is set to true, and `markdownContent` or `children` are set, then the component renders **EuiMarkdownFormat** text. Otherwise the component will render the **EuiMarkdownEditor**. The height of the component can be set, but in order the control the width of the component, you can place the `<Markdown />` component in another component.
 Markdown extends all the EuiMarkdownEditorProps except for the `editorId`, `uiPlugins`, and `MarkdownFormatProps`.
+Like the legacy React `<Markdown>` component, `style` can be set but will only be passed to **EuiMarkdownFormat**.
 
 ## Component Properties 
 

packages/shared-ux/markdown/impl/markdown.test.tsx

@@ -33,4 +33,16 @@ describe('shared ux markdown component', () => {
     render(<Markdown markdownContent={exampleMarkdownContent} />);
     expect(screen.getByTestId('euiMarkdownEditorToolbar')).toBeInTheDocument();
   });
+
+  it('renders EuiMarkdownEditor without style passed', () => {
+    render(<Markdown style={{ color: 'red' }} data-test-subj="editor" />);
+    expect(screen.getByTestId('editor')).not.toHaveStyle({ color: 'red' });
+  });
+
+  it('renders EuiMarkdownFormat with style passed', () => {
+    render(
+      <Markdown style={{ color: 'red' }} data-test-subj="format" markdownContent="test" readOnly />
+    );
+    expect(screen.getByTestId('format')).toHaveStyle({ color: 'red' });
+  });
 });

packages/shared-ux/markdown/impl/markdown.tsx

@@ -93,6 +93,8 @@ export const Markdown = ({
         parsingPluginList={_parsingPlugins}
         processingPluginList={openLinksInNewTab ? processingPlugins : undefined}
         data-test-subj={restProps['data-test-subj']}
+        // There was a trick to pass style as a part of props in the legacy React <Markdown> component
+        style={restProps.style}
       >
         {children ?? markdownContent!}
       </EuiMarkdownFormat>