[feature] Implement /api/v1/instance/peers endpoint (#660)

* add missing license headers

* start adding instance peers get

* rename domainblock.go

* embed domain in domainblock so it can be reused

* update swagger docs

* add test instances to db

* update tests

* add/update instancepeersget

* update domain model

* add getinstancepeers to db

* instance-expose-peers, instance-expose-suspended

* add auth checks for both current filters

* attach endpoint to router

* include public comment

* obfuscate domain if required

* go mod tidy

* update swagger docs

* remove unnecessary comment

* return 'flat' peerlist if no query params provided

internal/processing/admin/importdomainblocks.go

@@ -55,7 +55,7 @@ func (p *processor) DomainBlocksImport(ctx context.Context, account *gtsmodel.Ac
 
 	blocks := []*apimodel.DomainBlock{}
 	for _, d := range d {
-		block, err := p.DomainBlockCreate(ctx, account, d.Domain, false, d.PublicComment, "", "")
+		block, err := p.DomainBlockCreate(ctx, account, d.Domain.Domain, false, d.PublicComment, "", "")
 
 		if err != nil {
 			return nil, err