title: String matching query in flutterfire firestore
body: <p>I am trying to get all records having a particular email value. Here <code>email1</code> is user provided.</p>
  <p>I have tried :</p>
  <pre><code>QuerySnapshot userList = await  users!.where('email', '&gt;=', email1).where('email', '&lt;=', email1).get(); \\ gives syntax error
  
  users!.where(&quot;email&quot;, isGreaterThan: email1).get(); \\ returns all records
  
  users!.where(&quot;email&quot;, isGreaterThan: email1).where(&quot;email&quot;, isLessThan: email1).get(); \\ returns no record
  
  users!.where('email', arrayContainsAny: [email1]).get() \\ returns no record
  </code></pre>
  <p>Any help in this regard would be appreciated.</p>