Diagnostics in `analysis_options.yaml` about include

[FMorschel]

Somewhat related to #60125 (analysis_options.yaml diagnostics):

• Create a Flutter project
• Add lints as a dev dependency
• In your analysis_options.yaml do:

include:
  - package:flutter_lints/flutter.yaml
  - package:lints/recommended.yaml
  - package:lints/recommended.yml # Intentionally wrong here

Now you'll see:

Warning in the included options file C:\Users\felip_0vh5fa6\.puro\shared\pub_cache\hosted\pub.dev\lints-5.1.1\lib\recommended.yaml(71..30): The file includes itself recursively.dart(included_file_warning)

The include file 'package:lints/recommended.yml' in 'D:\dev\flutter\bug\analysis_options.yaml' can't be found when analyzing 'D:\dev\flutter\bug'.dart(include_file_not_found)

1. The first diagnostic is incorrect, we are including the same file (package:lints/recommended.yaml) as the first include.
2. All diagnostics show at the range of the first include (which is very unfortunate in cases where the user has incorrectly spelt the include).

CC @bwilkerson @pq

[bwilkerson]

Those certainly look like bugs to me.