Add tracker view using kanbam board by state

[timbl]

Like Jira, github etc boards

[josephguillaume]

Current implementation does provide a tab in which renderBoard shows issues as cards and allows drag and drop.
In renderIssueCard the color of the card is currently taken from first listed state or category with a ui:backgroundColor and could instead be customised.
https://github.com/solid/issue-pane/blob/a354a4a496c416886984ceb5b4c765b35fec8019/issue.js#L32