Support for Import issues from XML

There is currently only support for importing issues from CSV. This is problematic for two reasons:

• Files cannot be human readable, as well as machine readable, limiting the use-case of CSV data to one use-case
• A fix separator means that fields cannot contain that separator, or the import breaks

These problems cannot be addressed within the format of CSV. Hence, support form a bulk-create/issue-import from XML is needed.

Examples of bugs caused or related to the lack of an import from XML functionality: 

• https://jira.atlassian.com/browse/JSDCLOUD-1335
• https://jira.atlassian.com/browse/JRACLOUD-68996
• https://jira.atlassian.com/browse/JRACLOUD-66843
• https://jira.atlassian.com/browse/JRACLOUD-62414
• https://jira.atlassian.com/browse/JRACLOUD-64428
• https://jira.atlassian.com/browse/JRACLOUD-64636