Unified views for Project and Personal snippets

The unification happened in abstracting the shared functionality
(pretty much all of it) into a shared file to have one SSOT for
both views

app/assets/javascripts/pages/projects/snippets/show/index.js

-import initNotes from '~/init_notes';
-import ZenMode from '~/zen_mode';
-import LineHighlighter from '~/line_highlighter';
-import BlobViewer from '~/blob/viewer';
-import snippetEmbed from '~/snippet/snippet_embed';
-import { SnippetShowInit } from '~/snippets';
-
-document.addEventListener('DOMContentLoaded', () => {
-  if (!gon.features.snippetsVue) {
-    new LineHighlighter(); // eslint-disable-line no-new
-    new BlobViewer(); // eslint-disable-line no-new
-    initNotes();
-    new ZenMode(); // eslint-disable-line no-new
-    snippetEmbed();
-  } else {
-    SnippetShowInit();
-    initNotes();
-  }
-});
+import '~/snippet/snippet_show';

app/assets/javascripts/pages/snippets/show/index.js

-import LineHighlighter from '~/line_highlighter';
-import BlobViewer from '~/blob/viewer';
-import ZenMode from '~/zen_mode';
-import initNotes from '~/init_notes';
-import snippetEmbed from '~/snippet/snippet_embed';
-import { SnippetShowInit } from '~/snippets';
-
-document.addEventListener('DOMContentLoaded', () => {
-  if (!gon.features.snippetsVue) {
-    new LineHighlighter(); // eslint-disable-line no-new
-    new BlobViewer(); // eslint-disable-line no-new
-    initNotes();
-    new ZenMode(); // eslint-disable-line no-new
-    snippetEmbed();
-  } else {
-    SnippetShowInit();
-    initNotes();
-  }
-});
+import '~/snippet/snippet_show';

app/assets/javascripts/snippet/snippet_show.js

+import LineHighlighter from '~/line_highlighter';
+import BlobViewer from '~/blob/viewer';
+import ZenMode from '~/zen_mode';
+import initNotes from '~/init_notes';
+import snippetEmbed from '~/snippet/snippet_embed';
+import { SnippetShowInit } from '~/snippets';
+
+document.addEventListener('DOMContentLoaded', () => {
+  if (!gon.features.snippetsVue) {
+    new LineHighlighter(); // eslint-disable-line no-new
+    new BlobViewer(); // eslint-disable-line no-new
+    initNotes();
+    new ZenMode(); // eslint-disable-line no-new
+    snippetEmbed();
+  } else {
+    SnippetShowInit();
+    initNotes();
+  }
+});