Add Dameng database support to the CAP project.

[findersky]

Description:

This PR is mainly to provide support for the Dameng database in the CAP project. Why did we add support for the Dameng database? We have been using the CAP project, and according to the requirements, we needed to migrate the existing MySQL database to the Dameng database. Since there is currently no existing support for the Dameng database in the official CAP project, we have completed the support for the Dameng database in the CAP project.This PR only adds the DotNetCore.CAP.DM and Sample.RabbitMQ.DM projects and does not make any changes to the existing projects.

Issue(s) addressed:

Changes:

• Add a new project named DotNetCore.CAP.DM to provide Dameng database support for the CAP project.
• Add a sample project named Sample.RabbitMQ.DM to perform simple testing on the DotNetCore.CAP.DM project.

Affected components:

• Does not affect any of the existing components.

How to test:

• Provided the sample project Sample.RabbitMQ.DM.

Additional notes (optional):

Checklist:

• I have tested my changes locally
• I have added necessary documentation (if applicable)
• I have updated the relevant tests (if applicable)
• My changes follow the project's code style guidelines

Reviewers:

[yang-xiaodong]

Thank you for your PR.

Regarding the support of dameng database, we replied in the past issue. Please refer #1555 (comment).

[findersky]

express understanding