move toolbar out of the way

[ErikKrause]

Wonderful to have ThreadVis again!
It would be very nice to have the possibility to arrange the message header toolbar vertically on the left or right of the window. The old Compact Header add-on used to provide this feature for older versions.
Thunderbird 102 on Windows 10 pro

[ErikKrause]

I messed a bit with CSS in TB devtools (just to see whether it's feasible) and got this result:

These are the changes:

/* messageHeader.css | chrome://messenger/skin/shared/messageHeader.css */

.message-header-row.header-row-reverse {
  /* flex-direction: row-reverse; */
  flex-direction: row;
}

.header-buttons-container {
  /* display: flex; */
  display: block;
  position: absolute;
  top: 0;
  left: -19px;
}

.message-header-container, .message-header-extra-container {
  margin-left: 36px;
}

/* Element | chrome://messenger/content/messenger.xhtml */

#headerSenderToolbarContainer {
  /* display: flex; */
  position: relative;
}

/* Element | chrome://messenger/content/messenger.xhtml */

.messagepane-container {
  margin-left: 42px;
}

#messageHeader[show_header_mode="all"], #messageHeader.scrollable {
	overflow-y: unset;
	overflow-x: unset;
	max-height: 14em;
}