Let admins manually retry syncing TaxJar transactions

[benjaminwil]

What is the goal of this PR?

Solidus admin users may need to re-sync an order that failed to sync with TaxJar when it was shipped or recalculated last. This pull request exposes a "Retry" button in the list of transaction sync logs if the latest sync log has an error asociated with it.

How do you manually test these changes? (if applicable)

1. Create and ship an order with two or more line items.
   • [x] See it sync to the TaxJar reporting dashboard.
   • [x] See the successful sync log in the Solidus admin (Orders -> My Order -> TaxJar Sync History).
2. Make changes to the order to make it invalid to TaxJar. (For example, make the tax address zipcode totally invalid.)
3. Return one of the line items to force a new order transaction sync with TaxJar.
   • [x] See the unsuccessful syng log in the Solidus admin.
   • [x] See the "Retry" button.
4. Resolve the issue with the order (i.e. the zipcode).
5. Press the "Retry" button.
   • [x] See it sync to the TaxJar reporting dashboard.
   • [x] See the successful or unsuccessful sync log in the Solidus admin (Orders -> My Order -> TaxJar Sync History).

Merge Checklist

• [x] Run the manual tests
• [x] Update the changelog

Screenshots

[benjaminwil]

Will comment when I've finished the manual testing.

[forkata]

@benjaminwil Is this ready to be merged? If we need more testing can we pull the last commit into a separate PR 🙏🏼

[benjaminwil]

@forkata I just have to sit down and do the manual tests.

[benjaminwil]

Manual testing is complete. ✨

[forkata]

@benjaminwil Great work here! I think we still need one more rebase, now that #225 has been merged.