Replace removed 'copy-to-clipboard' icon (#8853)

The 'copy-to-clipboard' icon was removed in #8190, and replaced with a
new 'Copy' icon component. It was still being used in two places
though, on the confirmation page for decryption and on the reveal seed
phrase screen..

The new Copy icon is now used in these two places instead. It has been
given a size of '17' to match the old icon size.

ui/app/components/ui/export-text-container/export-text-container.component.js

@@ -2,6 +2,7 @@ import React, { Component } from 'react'
 import PropTypes from 'prop-types'
 import copyToClipboard from 'copy-to-clipboard'
 import { exportAsFile } from '../../../helpers/utils/util'
+import Copy from '../icon/copy-icon.component'
 
 class ExportTextContainer extends Component {
   render () {
@@ -20,7 +21,7 @@ class ExportTextContainer extends Component {
             className="export-text-container__button export-text-container__button--copy"
             onClick={() => copyToClipboard(text)}
           >
-            <img src="images/copy-to-clipboard.svg" alt="" />
+            <Copy size={17} color="#3098DC" />
             <div className="export-text-container__button-text">
               {t('copyToClipboard')}
             </div>

ui/app/pages/confirm-decrypt-message/confirm-decrypt-message.component.js

@@ -7,6 +7,7 @@ import AccountListItem from '../send/account-list-item/account-list-item.compone
 import Button from '../../components/ui/button'
 import Identicon from '../../components/ui/identicon'
 import Tooltip from '../../components/ui/tooltip-v2'
+import Copy from '../../components/ui/icon/copy-icon.component'
 
 import { ENVIRONMENT_TYPE_NOTIFICATION } from '../../../../app/scripts/lib/enums'
 import { getEnvironmentType } from '../../../../app/scripts/lib/util'
@@ -273,7 +274,7 @@ export default class ConfirmDecryptMessage extends Component {
                 >
                   {t('decryptCopy')}
                 </div>
-                <img src="images/copy-to-clipboard.svg" />
+                <Copy size={17} color="#3098DC" />
               </Tooltip>
             </div>
           )