title: Insert Material-UI Icon into Input Field in React
body: <p>Hi I am using a datepicker from Material-UI Datepickers. 
  Using the Inline datepickers they provide I want to insert a calendar Icon into the input field. </p>
  
  <p>this is what the input element looks like. How can I add an I con to the input field here. So that it still shows inside the element and clicking it will activate the inputfield but will not disrupt the value of the input.</p>
  
  <pre><code>              &lt;InlineDatePicker
                  label={"Start Date"}
                  value={startDate}
                  format={"MMM Do YYYY"}
                  onChange={(e) =&gt; {this.handleDateChange(e, 'start')}}
                  className={styles.dateInput}
                  minDate={this.getMinDate(true)}
                  maxDate={this.getMaxDate(true)}
                /&gt;
  </code></pre>