Fix ecosystem account switching : add support for additional account formats

[sowjanyakch]

STR:

• have account A (abc@cloud.com@example.inst2.cloud.com) on talk app
• in talk app, tap on files icon
• fails with message "Invalid account format. Must be an email".

This bug is also observed in files and notes app.

Exception: Ecosystem apps should support multiple valid account formats.

This PR supports additional account formats:

abc@cloud.com@example.inst2.cloud.com
admin@10.0.2.2:55002
admin@10.0.2.2

[alperozturk96]

I tested for

abc@cloud.com@example.inst2.cloud.com
admin@10.0.2.2

Screen.Recording.2026-02-26.at.08.54.12.mp4

All working except Talk client not using EcosystemManager.receiveAccount() thus selected account is not opening in the Talk but this needs to be implemented in Talk client separately.

[nickvergessen]

Nextcloud can also be installed in a folder, so also test@example.tld@cloud.example.tld:443/subfolder/deep would be a valid cloud id

[nickvergessen]

Don't need to wait for my approval here. test looks good