fix(rn,shared-video,invite-dialog) fix placehoolder text color to be visible

react/features/invite/components/add-people-dialog/native/AddPeopleDialog.js

     type Item
 } from '../../../../base/react';
 import { connect } from '../../../../base/redux';
+import { ColorPalette } from '../../../../base/styles';
 import { beginShareRoom } from '../../../../share-room';
 import { ADD_PEOPLE_DIALOG_VIEW_ID, INVITE_TYPES } from '../../../constants';
 import AbstractAddPeopleDialog, {
                         placeholder = {
                             this.props.t(`inviteDialog.${placeholderKey}`)
                         }
+                        placeholderTextColor = { ColorPalette.lightGrey }
                         ref = { this._setFieldRef }
                         style = { styles.searchField }
                         value = { this.state.fieldValue } />

react/features/shared-video/components/native/SharedVideoDialog.js

 
 import { InputDialog } from '../../../base/dialog';
 import { connect } from '../../../base/redux';
+import { ColorPalette } from '../../../base/styles';
 import { defaultSharedVideoLink } from '../../constants';
 import AbstractSharedVideoDialog from '../AbstractSharedVideoDialog';
 
                 contentKey = 'dialog.shareVideoTitle'
                 onSubmit = { this._onSubmitValue }
                 textInputProps = {{
-                    placeholder: defaultSharedVideoLink
+                    placeholder: defaultSharedVideoLink,
+                    placeholderTextColor: ColorPalette.lightGrey
                 }} />
         );
     }