Print simulator lists before throwing exceptions

[jmagman]

When simulator runtime or devices are not found, print the failing output to show what simulators are available. Useful for LUCI Xcode cipd package introspection.

Will help figure out what simulators are available when upgrading Xcode on the builders:
https://logs.chromium.org/logs/flutter/led/magder_google.com/5e74b39e0a9f1bdc682c8d81f3d8baca2431d9547882e7eaf9cbde48e89daf9b/+/u/test:_felt_ios-safari_test/stdout

Pre-launch Checklist

• I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
• I read the [Tree Hygiene] wiki page, which explains my responsibilities.
• I read the [Flutter Style Guide] recently, and have followed its advice.
• I signed the [CLA].
• I listed at least one issue that this PR fixes in the description above.
• I updated/added relevant documentation (doc comments with ///).
• I added new tests to check the change I am making, or this PR is [test-exempt].
• All existing and new tests are passing.

[yjbanov]