[feature] Improve package signing plugin integration: new commands, tools and output format

[danimtb]

Changelog: Feature: Improve package signing plugin integration.
Changelog: Feature: Add conan cache sign and conan cache verify commands for package signing.
Changelog Feature: Standardize package summary format with files, checksums, signing method and signing provider.
Docs: missing

• Added new commands for sign and verify.
• Added text and json format output.
• Manage errors and messages (warnings too) for the report.
• Added context parameter to decide the behavior of the plugin when uploading, installing or just managing the signatures from the cache.
• Added tools to create a package summary json file wtih files, checkusms, signing methof and signing provider.