Add maven profile to support packaging source code

[slievrly]

Add maven profile to support packaging source code.
The file name after packaging: apache-seata-${version}-incubating-src.tar.gz

Modules to be ignored:

• .github
• distribution
• test-old-version
• test

[WangzJi]

Hi, I'd like to take this issue. Please assign it to me if it's available.