[MM-54791]: Convert email icon component to function component (#25548)

* refactor: convert email icon to rfc

* chore: update snapshot

webapp/channels/src/components/admin_console/system_user_detail/__snapshots__/system_user_detail.test.tsx.snap

@@ -36,7 +36,7 @@ exports[`components/admin_console/system_user_detail should match default snapsh
               Email
             </span>
             <div>
-              <EmailIcon
+              <Memo(EmailIcon)
                 className="SystemUserDetail__field-icon"
               />
               <input
@@ -272,7 +272,7 @@ exports[`components/admin_console/system_user_detail should match snapshot if LD
               Email
             </span>
             <div>
-              <EmailIcon
+              <Memo(EmailIcon)
                 className="SystemUserDetail__field-icon"
               />
               <input
@@ -510,7 +510,7 @@ exports[`components/admin_console/system_user_detail should match snapshot if MF
               Email
             </span>
             <div>
-              <EmailIcon
+              <Memo(EmailIcon)
                 className="SystemUserDetail__field-icon"
               />
               <input
@@ -754,7 +754,7 @@ exports[`components/admin_console/system_user_detail should match snapshot if SA
               Email
             </span>
             <div>
-              <EmailIcon
+              <Memo(EmailIcon)
                 className="SystemUserDetail__field-icon"
               />
               <input
@@ -992,7 +992,7 @@ exports[`components/admin_console/system_user_detail should match snapshot if no
               Email
             </span>
             <div>
-              <EmailIcon
+              <Memo(EmailIcon)
                 className="SystemUserDetail__field-icon"
               />
               <input
@@ -1228,7 +1228,7 @@ exports[`components/admin_console/system_user_detail should match snapshot if us
               Email
             </span>
             <div>
-              <EmailIcon
+              <Memo(EmailIcon)
                 className="SystemUserDetail__field-icon"
               />
               <input

webapp/channels/src/components/widgets/icons/email_icon.tsx

@@ -3,10 +3,11 @@
 
 import React from 'react';
 
-export default class EmailIcon extends React.PureComponent<React.HTMLAttributes<HTMLSpanElement>> {
-    render() {
+type Props = React.HTMLAttributes<HTMLSpanElement>;
+
+const EmailIcon: React.FC<Props> = (props) => {
     return (
-            <span {...this.props}>
+        <span {...props}>
             <svg
                 width='100%'
                 height='100%'
@@ -19,5 +20,6 @@ export default class EmailIcon extends React.PureComponent<React.HTMLAttributes<
             </svg>
         </span>
     );
-    }
-}
+};
+
+export default React.memo(EmailIcon);