feat: add plugins DashPay and DashPaySyncWorker

[Alex-Werner]

Issue being fixed or feature implemented

This PR adds two plugins DashPay and DashPaySyncWorker to DashJS. These are automatically started on a HDWallet initialized address in order to sync contacts.

What was done?

• feat: introduce DashPaySyncWorker
• feat: introduce DashPay Plugin

How Has This Been Tested?

• Provided unit tests

Breaking Changes

N/A

Checklist:

• [X] I have performed a self-review of my own code
• [X] I have commented my code, particularly in hard-to-understand areas
• [X] I have added or updated relevant unit/integration/functional/e2e tests
• [ ] I have made corresponding changes to the documentation

For repository code-owners and collaborators only

• [ ] I have assigned this pull request to a milestone

[lgtm-com[bot]]

This pull request introduces 2 alerts when merging 24a27b8e6991603da9f1e921859127cf8e8bc17e into 7802f90084735c77b7ce9ac44681f5ee13bfff6c - view on LGTM.com

new alerts:

• 2 for Unused variable, import, function or class

[lgtm-com[bot]]

This pull request introduces 2 alerts when merging d2d996fb2b134daaeacb12877c2d80520a203008 into 7802f90084735c77b7ce9ac44681f5ee13bfff6c - view on LGTM.com

new alerts:

• 2 for Unused variable, import, function or class

[lgtm-com[bot]]

This pull request introduces 1 alert when merging 16599c45c9abbbe22baac51c9df7282849cb0f6c into 9ad543205407c35d4458b5b1ee03fe6bd8f87bf1 - view on LGTM.com

new alerts:

• 1 for Unused variable, import, function or class