Make EC widget theme reactive - Update widget url when the theme changes (#12295)

* update widget url when the theme changes

Signed-off-by: Timo K <toger5@hotmail.de>

* quick "make it EC specific" workaround proposal.

Signed-off-by: Timo K <toger5@hotmail.de>

* use `matches`

Signed-off-by: Timo K <toger5@hotmail.de>

* test coverage

Signed-off-by: Timo K <toger5@hotmail.de>

* more test coverage

Signed-off-by: Timo K <toger5@hotmail.de>

* fix jest

Signed-off-by: Timo K <toger5@hotmail.de>

* add tests for theme changes

Signed-off-by: Timo K <toger5@hotmail.de>

* update snapshots

Signed-off-by: Timo K <toger5@hotmail.de>

* test for theme update with non ec widget

Signed-off-by: Timo K <toger5@hotmail.de>

* add dark custom theme widget url

Signed-off-by: Timo K <toger5@hotmail.de>

* trigger conditions for theme cleanup

Signed-off-by: Timo K <toger5@hotmail.de>

* update tests using testId

Signed-off-by: Timo K <toger5@hotmail.de>

* use typed event emitter for theme watcher

Signed-off-by: Timo K <toger5@hotmail.de>

* simplify condition

Signed-off-by: Timo K <toger5@hotmail.de>

---------

Signed-off-by: Timo K <toger5@hotmail.de>