Add a title to the iframe

As mentioned already on slack. the changes look good. thank you! i've applied the diff and tested on macos 12.6.1 with voiceover on safari, firefox and edge. a screenshot in safari:

i think we have to wait for feedback if the string might be too verbose as already noted and maybe a more concise title would be the better choice. but that could be changed easily at a later point. but i like it in the current state.

the only detail that worries me a little bit but i was unable to find something on so far is that in edge sometimes the frames section in the voiceover rotor isnt shown at all and if it is shown it is showing the following even-though the iframe shows the correct title in the devtools:

@rkoller given that feedback it's unclear if you think this is RTBC or not. Please modify the Status of the issue if either you think it needs work or is RTBC

hm i was drawn. the string itself looks good. in particular using a colon was a good idea, since it adds a slight pause in the announcement separating the node bundle name from the actual title. in my initial suggestion that wasn't in. so that is an improvement.

about the length and verbosity of the string we have to wait for actual screenreader user feedback if it needs to be more concise.

and about the detail about edge. it looks like edge isnt showning any frame in the rotor per default, if i click into the frame and then open the rotor the frame is shown. but it isnt using the title of the iframe but the title of head inside the iframe it looks like.

so i think the title could be still shortened in a follow up in case it is too verbose and in regards of the edge issue i will ask over in the edge issue queue. but since other browsers behave as expected that could also be something for a follow up issue.

just thought maybe someone else would chime into the discussion. but setting it to rtbc now.

I feel that's a good pragmatic approach. This improvement is better than nothing, and we can expand it in the future. Glad we could get this in the MVP.