Properly handle more than 4 fields in EditProfileViewModel (#4936)

Also read `configuration.accounts.max_profile_fields` from
`api/v2/instance` to get the correct limit for GoToSocial.

Glitch-soc also allows more fields but does not provide configuration
yet, see https://github.com/glitch-soc/mastodon/issues/2973

closes https://github.com/tuskyapp/Tusky/issues/3305

app/src/test/java/com/keylesspalace/tusky/components/compose/ComposeActivityTest.kt

@@ -599,7 +599,7 @@ class ComposeActivityTest {
     private fun getConfiguration(maximumStatusCharacters: Int?, charactersReservedPerUrl: Int?): Instance.Configuration {
         return Instance.Configuration(
             Instance.Configuration.Urls(),
-            Instance.Configuration.Accounts(1),
+            Instance.Configuration.Accounts(maxFeaturedTags = 1, maxProfileFields = 4),
             Instance.Configuration.Statuses(
                 maximumStatusCharacters ?: InstanceInfoRepository.DEFAULT_CHARACTER_LIMIT,
                 InstanceInfoRepository.DEFAULT_MAX_MEDIA_ATTACHMENTS,