Support wildcard patterns in RoleARN mappings

[AndreKurait]

What

Extend RoleMapping.Matches() to use ArnLike() for wildcard matching when the RoleARN contains * or ? characters.

Why

The ArnLike matching infrastructure already exists in the codebase (used for SSO role matching via SSOArnLike()) but is not wired up for regular RoleARN mappings, which only support exact string matching via strings.EqualFold().

This means there is no way to map a pattern of roles (e.g., all roles with a dev- prefix, or all roles in an account) without enumerating each one individually. The SSO feature (issue #333) proved the ArnLike approach works — this PR generalizes it to regular role mappings.

Example

mapRoles:
- rolearn: "arn:aws:iam::012345678912:role/dev-*"
  username: "dev-{{SessionName}}"
  groups:
  - developers
- rolearn: "arn:aws:iam::012345678912:role/*"
  username: "{{SessionName}}"
  groups:
  - all-roles

Changes

• pkg/config/mapper.go: RoleMapping.Matches() now delegates to arn.ArnLike() when the RoleARN contains wildcard characters, falling back to exact match for non-wildcard ARNs (no behavior change for existing configs)
• pkg/mapper/file/mapper.go: NewFileMapper skips arn.Canonicalize() for wildcard RoleARNs (the AWS ARN parser rejects wildcards) and stores them lowercased instead
• Tests: Added for both unit (Matches) and integration (FileMapper.Map) levels covering prefix wildcards, full wildcards, cross-account rejection, and cross-resource-type rejection

Backward Compatibility

• Non-wildcard RoleARN mappings are completely unchanged (exact strings.EqualFold path)
• No new feature flags required — wildcard detection is automatic based on the presence of * or ? in the configured RoleARN
• The ArnLike function is already well-tested in the existing SSO code path

Testing

All existing tests pass. New tests added:

• TestWildcardRoleARNMapping — full wildcard role/*, cross-account rejection, cross-resource-type rejection
• TestWildcardRoleARNPrefixMapping — prefix wildcard role/dev-*
• TestWildcardRoleMap — end-to-end through FileMapper.Map()

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: AndreKurait / name: Andre Kurait (b0e0129)

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[bryantbiggs]

/ok-to-test

[AndreKurait]

@bryantbiggs did the test finish? Any other changes needed to get this in?