Unused deplicated

[Hmikihiro]

Issue #, if available:#17

Description of changes:
This PR adds functionality to:

1. Warn about unused approval patterns in allowed_external_types.
2. Warn about duplicated approval patterns that match the same type.

For example:

pub use foo::bar;

allowed_external_types = ["foo::*", "foo::bar"]

Here, foo::bar matches both "foo::*" and "foo::bar". However, only "foo::*" is necessary. With this PR, a warning is issued when multiple patterns match the same type. This helps in reducing redundant definitions in configuration.

Additionally, a warning is also issued for patterns in allowed_external_types that do not match any type in the public API.

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