[ODS] Add support for whitespaces inside <text:span>

The `<text:p>` node can contain the string value directly or contain child elements. In this case, whitespaces contain in the child elements should be replaced by their XML equivalent:
 - space => `<text:s />`
 - tab => `<text:tab />`
 - line break => `<text:line-break />`

@see https://docs.oasis-open.org/office/v1.2/os/OpenDocument-v1.2-os-part1.html#__RefHeading__1415200_253892949

tests/Spout/Reader/ODS/ReaderTest.php

@@ -277,6 +277,17 @@ class ReaderTest extends TestCase
         $this->assertEquals([$expectedRow], $allRows);
     }
 
+    /**
+     * @return void
+     */
+    public function testReadShouldSupportWhitespaceAsXML()
+    {
+        $allRows = $this->getAllRowsForFile('sheet_with_whitespaces_as_xml.ods');
+
+        $expectedRow = ["Lorem  ipsum\tdolor sit amet"];
+        $this->assertEquals([$expectedRow], $allRows);
+    }
+
     /**
      * @NOTE: The LIBXML_NOENT is used to ACTUALLY substitute entities (and should therefore not be used)
      *