Features/group badges

Fix type for ApprovalsBeforeMerge

ApprovalsBeforeMerge denotes the number of approvals required before
merging and will never have the type `bool`. This change updates the
type for the field and adds test coverage for the type.

Add GetProjectOptions to support additional attributes

Add mirror related fields to Project struct

add WIP to ListProjectMergeRequestOptions as well

add "in" & "wip" to merge request options

add web_url pipeline response

Split PlatformKubernetesOptions to add and edit struct

ADD ReadmeURL to Project struct

Add project clusters API support

Add custom attributes to groups, users and projects apis

Fix ISOTime encoding in GET requests

Removes `url` struct tags from ContributionEvent and combines two checks
in one line.
Signed-off-by: Sune Keller <absukl@almbrand.dk>

Also implement the query.Encoder interface on ISOTime.
Signed-off-by: Sune Keller <absukl@almbrand.dk>

Event dates should be in the format YYYY-MM-DD

Fix the board list label field

It needs to be a single label, not a slice of labels.