Deprecation of search enpoints

[briavers]

As declared in https://developer.atlassian.com/changelog/#CHANGE-2046

the /search endpoints will be removed as of may 1st Is there any plan for an update?

[herbdool]

The endpoints to use now are GET or POST of /rest/api/3/search/jql. I only just became aware of this so I'm scrambling for a replacement if this library doesn't yet support it.

[herbdool]

I created a PR which works for my use case: #97. It works with a simple JQL.

Might be useful to also implement the new bulk fetch: https://developer.atlassian.com/cloud/jira/platform/rest/v3/api-group-issues/#api-rest-api-3-issue-bulkfetch-post and the count api: https://developer.atlassian.com/cloud/jira/platform/rest/v3/api-group-issue-search/#api-rest-api-3-search-approximate-count-post

[herbdool]

I ended up including the bulk fetch and count. It's working for me.

[herbdool]

In my testing using bulkFetch() has a significant performance improvement over get(), so I hope that it also gets merged in since the new search API won't return all the necessary fields (for our use case).

bulkFetch(): 0.04s per issue; get(): 0.4s per issue. So a ten times improvement.

[herbdool]

@lesstif can you take a look at this PR? Does it look good or need some improvement?