Refine sign in flow to match designs and iOS flow (#100)

* Fix dark theme

* First attempt at replicating iOS' UI & flows.

* Try to fix Maestro tests

* Add error dialogs and tests

* Remove unused modifiers

* Try to fix detekt issues

* Tidy up maestro login flow a bit

* Add `CompoundColorPalette` with some needed colors

* Fixes to designs

* Fix detekt issues

* More design fixes

* Some other minor design fixes

* Add changelog

* Minor tweaks.

* Remove legacy dark material theme as it's no longer needed.

* Move sliding sync 'learn more' url to constants object

* Remove unused focusManager

* Change how the displayed homeserver works

* Keep user input as homeserver if it's valid

* Remove `CompoundColorPalette`, try to fix issue when toggling dark mode.

* Add `@Stable` to the theme, adjust how it toggles in dark mode

* Remove unused strings

* Update screenshots

* Re-organize components in LoginRootScreen

* Bump min coverage to 55, max to 60

* Always replace the snapshots contents when running `recordPaparazzi`

* Fix dark theme preview of components using content colors

* Add `BackButton` component

* Handle errors with dialogs in a generic way

* Align our Dialog components with the designs, use them were needed

* Use a `MatrixHomeserverDetails` data class instead of just an URL.

* `AuthenticationService.getHomeserverDetails()` now returns a `StateFlow`.

Also, try to fix coverage issues in tests.

.maestro/tests/account/changeServer.yaml

@@ -1,5 +1,6 @@
 appId: ${APP_ID}
 ---
-- tapOn: "Change"
+- tapOn:
+    id: "login-change_server"
 - takeScreenshot: build/maestro/200-ChangeServer
 - tapOn: "Continue"

.maestro/tests/account/login.yaml

@@ -5,17 +5,14 @@ appId: ${APP_ID}
 - takeScreenshot: build/maestro/100-SignIn
 - runFlow: changeServer.yaml
 - runFlow: ../assertions/assertLoginDisplayed.yaml
-- tapOn: "Username or email"
-# ios
-# - tapOn:
-#     id: "usernameTextField"
-#     index: 0
+- tapOn:
+    id: "login-email_username"
 - inputText: ${USERNAME}
+- pressKey: Enter
 - tapOn: "Password"
-# iOS
-#- tapOn:
-#    id: "passwordTextField"
-#    index: 0
+- tapOn:
+    id: "login-password"
 - inputText: ${PASSWORD}
+- pressKey: Enter
 - tapOn: "Continue"
 - runFlow: ../assertions/assertHomeDisplayed.yaml