feat: add AllPermissionKeys type for i18n label keys in permission schema

[mj-kiwi]

📝 Description

Adds an AllPermissionKeys exported type in @metamask/7715-permission-types — a union of all i18n labelKey string literals used across permission schema field definitions.

🔄 What Changed?

• Added AllPermissionKeys union type (21 label key literals) in permissions/schema/types.ts
• Tightened BaseField.labelKey from string to AllPermissionKeys
• Exported AllPermissionKeys from permissions/schema/index.ts and the package root index.ts

🚀 Why?

• Consumers (e.g. the extension) need a typed key set to build exhaustive Record<AllPermissionKeys, string> i18n maps, so new label keys fail to compile until translations are added
• Tightening labelKey from string catches typos/unknown keys in schema field definitions at compile time

🧪 How to Test?

• Manual testing steps:

1. yarn tsc --noEmit in packages/7715-permission-types — should pass
2. yarn build in packages/7715-permission-types — should succeed
3. Import AllPermissionKeys from @metamask/7715-permission-types in a consumer and confirm it resolves to the 21-key union

• Automated tests added/updated
• All existing tests pass

⚠️ Breaking Changes

• No breaking changes
• Breaking changes (describe below):

📋 Checklist

• Code follows the project's coding standards
• Self-review completed
• Documentation updated (if needed)
• Tests added/updated
• Changelog updated (if needed)
• All CI checks pass

🔗 Related Issues

Closes #
Related to #

📚 Additional Notes

AllPermissionKeys is currently a hand-maintained literal union mirrored from the labelKey strings used in sections.ts / tokenApprovalRevocation.ts / unknownPermissionType.ts. It will catch unknown-key typos at compile time, but won't catch dead/unused keys — fine at 21 entries, worth revisiting if this list grows and starts drifting.

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Note

Low Risk
Compile-time typing and public type exports only; no runtime behavior or security-sensitive logic changes.

Overview
Adds and exports AllPermissionKeys, a union of the 21 i18n labelKey literals used in permission schema field definitions, so consumers can build exhaustive translation maps (e.g. Record<AllPermissionKeys, string>).

BaseField.labelKey is narrowed from string to AllPermissionKeys, so schema definitions must use known keys at compile time. The type is re-exported from the schema module and @metamask/7715-permission-types package entry; the changelog documents the addition.

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