feat(Content): add m size (#1120)

* feat(Content): add m size 
* fix(Content): fix centered state

Author: benax-se

src/blocks/ContentLayout/__snapshots__/ContentLayout.visual.test.tsx-snapshots/ContentLayout-render-stories-Default-light-chromium-linux.png

@@ -72,6 +72,11 @@ const WithFilesTemplate: StoryFn<ContentLayoutBlockModel> = (args) => (
                     size: 'l',
                     textContent: {title: getSizeTitle('L'), ...args.textContent},
                 },
+                {
+                    ...args,
+                    size: 'm',
+                    textContent: {title: getSizeTitle('M'), ...args.textContent},
+                },
                 {
                     ...args,
                     size: 's',
@@ -91,6 +96,11 @@ const SizesTemplate: StoryFn<ContentLayoutBlockModel> = (args) => (
                     size: 'l',
                     textContent: {title: getSizeTitle('L'), ...args.textContent},
                 },
+                {
+                    ...args,
+                    size: 'm',
+                    textContent: {title: getSizeTitle('M'), ...args.textContent},
+                },
                 {
                     ...args,
                     size: 's',