[filesapp] Add utf8.txt integration test resource

Includes 🙂 face character, samples from different languages, Dingbats
and Math characters, Greek letters, Runes, etc:

  Hello नोपहिनस्ति أن 害
  色は匂へど 散りぬるを
  κόσμε ᚹᛦᛗ コンニチハ
  волн ապակի Կրնամ
  їсти मुझे |∊☀✌✂♁ 🙂

Note the file is pure text with no UTF-8 BOM (Byte Order Marks) at the
start of the file.

Not used in anywhere in the code as yet.

Bug: 1064855
No-try: true
Change-Id: I34409215ec22aacea6a872cbc87241f27ab35e03
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2425545
Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: François Degros <fdegros@chromium.org>
Reviewed-by: Jeremie Boulic <jboulic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809706}

chrome/test/data/chromeos/file_manager/utf8.txt

+Hello नोपहिनस्ति أن 害
+色は匂へど 散りぬるを
+κόσμε ᚹᛦᛗ コンニチハ
+волн ապակի Կրնամ
+їсти मुझे |∊☀✌✂♁ 🙂

ui/file_manager/integration_tests/test_util.js

@@ -724,6 +724,17 @@ const ENTRIES = {
     typeText: 'Plain text',
   }),
 
+  utf8Text: new TestEntryInfo({
+    type: EntryType.FILE,
+    sourceFileName: 'utf8.txt',
+    targetPath: 'utf8.txt',
+    mimeType: 'text/plain',
+    lastModifiedTime: 'Sep 4, 1998, 12:34 PM',
+    nameText: 'utf8.txt',
+    sizeText: '191 bytes',
+    typeText: 'Plain text',
+  }),
+
   mHtml: new TestEntryInfo({
     type: EntryType.FILE,
     sourceFileName: 'page.mhtml',