Add linkToMessage property to MessageActionsPayload class

[denscollo]

Fixes #622

Description

This pull request adds the linkToMessage property to the MessageActionsPayload class from BotBuilder-Schema library. By adding this property, it can add the link provided in the payload from MS-Teams.
Also, we added tests for the methods of the class.

Specific Changes

• Added the linkToMessage property to the MessageActionsPayload class from BotBuilder-Schema
• Created the MessageActionsPayloadTest.java file inside the test/teams folder of the library.
• Added tests for all the methods of the MessageActionsPayload in that test class.

Testing

In the following image, you can see the bot assigns the linkToMessage property when sharing a card in MS-Teams, using the 51.teams-messaging-extensions-action sample from the same repository.

And in the next image, you can see the added tests passing.

[tracyboehrer]

@JuanAr @santgr11 While not at all obvious, this PR is failing the build check due to some CheckStyle errors in Schema. If you perform a "mvn package" from the Java SDK root, it should generate a checkstyle-result.xml or pmd.xml in the libraries/botbuilder-schema/target folder.

[denscollo]

Thanks @tracyboehrer, we were reviewing the logs to find what the issue was. We'll work on this to have the PR ready. Thanks

[tracyboehrer]

@denscollo Thanks! This issue is on my list of things to correct. It throws everyone. I believe there is a way to make those errors more obvious without having to dig into the DevOps logs.

[denscollo]

@tracyboehrer We just pushed the styling fix and the build succedeed! Thanks 😄