Make tooltips keyboard accessible (#7281)

* show tooltips on hover in eventtile

Signed-off-by: Kerry Archibald <kerrya@element.io>

* use tooltip props pass thru

* use tooltiptarget in InfoTooltip

Signed-off-by: Kerry Archibald <kerrya@element.io>

* use target in TestWithTooltip

Signed-off-by: Kerry Archibald <kerrya@element.io>

* tsc fixes

Signed-off-by: Kerry Archibald <kerrya@element.io>

* test tooltip target

Signed-off-by: Kerry Archibald <kerrya@element.io>

* lint fix

Signed-off-by: Kerry Archibald <kerrya@element.io>

* rename tooltip handlers

Signed-off-by: Kerry Archibald <kerrya@element.io>

* update copyright to 2021

Signed-off-by: Kerry Archibald <kerrya@element.io>

src/components/views/rooms/EventTile.tsx

@@ -1203,7 +1203,7 @@ export default class EventTile extends React.Component<IProps, IState> {
             _t(
                 '<requestLink>Re-request encryption keys</requestLink> from your other sessions.',
                 {},
-                { 'requestLink': (sub) => <a onClick={this.onRequestKeysClick}>{ sub }</a> },
+                { 'requestLink': (sub) => <a tabIndex={0} onClick={this.onRequestKeysClick}>{ sub }</a> },
             );
 
         const keyRequestInfo = isEncryptionFailure && !isRedacted ?