Re-organize modules in ballerinax/salesforce package

[aashikam]

Description: This is due to confusion found using the existing structure during implementing a PoC. The ballerinax/salesforce package needs to be re-organized for more clarity from user perspective in the following structure.

ballerinax/salesforce 
     - soap 
     - apex 
     - bulkv1 
     - bulkv2 

ballerinax/salesforce - REST API
   -- modules
     - soap - SOAP API
     - apex - Apex API
     - bulkv1 - BULK API V1
     - bulkv2 - BULK API V2

Questions:

• [ ] Are we doing an API upgrade also with this?
• [ ] Do we need backwards compatibility - minor release? If so how? Are we adding duplicate APIs by deprecating existing ones?

High level tasks

• Reorganize and fix the build
• Fix the tests