Support changing your integration manager in the UI

[turt2live]

Fixes element-hq/element-web#10161 (this is the last of the PRs in the series for this issue)

Known missing from this PR:

• Terms handling (see Inline terms agreement on change IS and IM element-hq/element-web#10539)
• The tooltip is the wrong size (destined for a future PR, probably the one which fixes 10539)
• Unresolved TODO comments (destined for a future PR)

Based upon:

• Refactor integration manager handling into a common place #3301 merged
• Read integration managers from account data (widgets) #3302 merged
• Add UI in settings to change ID Server #3300 merged

Changeset: 03d735f. changed

Gif:

[dbkr]

Looks good. I'll leave you to figure out the field widths etc. I think the reason it fits for you here but didn't for me is that my window is narrower and so there isn't enough space to the right of the settings dialog so it goes off the screen.

[turt2live]

I'll adopt the use of the mixin and leave fixing it for element-hq/element-web#10554 (which I also plan to take on, just not here)

[turt2live]

@dbkr I've switched this over to using vector-namespaced widget types to avoid having to put MSC1957 through the queue (we only use about a third of it). Please take a quick look.

[dbkr]

Bleugh, then people will end up with this im.vector.integration_manager in the wild and we'll have to worry about the transition. I think that will ultimately make life even more complex. I'd rather not have it kicking around if at all possible - even if we have to disable this until the MSC is through.

[turt2live]

I'll just get the MSC through the process and start writing up the implementation we're missing.

[turt2live]

@dbkr done - now just not using vector-namespaced things

[dbkr]

Thanks - I've made the MSC slightly closer!