Restore macOs room header dragability

[germain-gg]

Fixes #1135

Checklist

• Ensure your code works with manual testing
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Here's what your changelog entry will look like:

🐛 Bug Fixes

• Restore macOs room header dragability (#1136). Fixes Room header icons unclickable #1135.

[t3chguy]

The text container for the room name in the room header should also be no-drag, like it is on legacy (its within the Accessible Button)

[germain-gg]

I'm not entirely sure it needs to be like that.
The new room header is not interactive the same way the old one way, therefore we can allow drag from that element.

In the spirit of moving that pull request forward i've pushed that change.

[t3chguy]

It'd mean you can't highlight the text which is not good for accessibility

[t3chguy]

See comment

[germain-gg]

Cross posting what I added to #element-dev:matrix.org

IMO we should not use the CSS classes we use for styling in order to set the draggability. It kinda hides intent, maybe using a data attribute or a electron- prefixed css class could help be more explicit and avoid this kind of regressions in the future?