[Fleet UI] Improve error message with Saved Object ID collision

[P1llus]

Stack version 8.7.1
For some reason, when an integration is in a broken state, for example during a stack upgrade, the reference between the installed integration and its related assets can be lost.

Whenever an integration is uninstalled, and the assets are not removed because of this, it will create a confusing error when trying to reinstall the integration:

Failure to install package [cloudflare_logpush]: [Error: Non-unique import objects detected: [dashboard:cloudflare_logpush-3da7bd20-dc45-11ec-b76d-adcfe05cc1fe,dashboard:cloudflare_logpush-87f6ad60-dc44-11ec-b76d-adcfe05cc1fe,dashboard:cloudflare_logpush-a32a0690-dc44-11ec-b76d-adcfe05cc1fe,dashboard:cloudflare_logpush-bb426420-dc44-11ec-b76d-adcfe05cc1fe,dashboard:cloudflare_logpush-cc375d30-dc44-11ec-b76d-adcfe05cc1fe,dashboard:cloudflare_logpush-da55ddb0-dc44-11ec-b76d-adcfe05cc1fe,dashboard:cloudflare_logpush-e7a24120-dc44-11ec-b76d-adcfe05cc1fe,search:cloudflare_logpush-a58b3a80-e257-11ec-b57d-b9b9d5221e36,search:cloudflare_logpush-dc01afe0-e24d-11ec-b57d-b9b9d5221e36]]

It also did not show in the UI to the user that the integration failed to install, but rather just never showed up in the "installed integrations" list.

Can we please have an error message saying that the Assets already exist? Or something in that regard, so it's easier to determine that there are some assets in limbo for some reason?
Even better, we could have a popup asking if the user wants to overwrite the assets or not maybe?

Steps to Reproduce:

1. Install any asset outside of the integration installation procedure.
2. Try to install the integration

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)

[juliaElastic]

Related to #161804