fix: cross-origin url cannot be redirected when "externalLinkTarget" is set to "_self" and "routerMode" is set to "history". (#1062)

* [fix #1046] fix cross-origin url cannot be redirected when  "externalLinkTarget" is set to "_self" and "routerMode" is set to "history".

* [code format] code format.

* update docs

* docs refine.

* fix(core): cross-orgin link work incorrect (#1046)

Fix cross-origin url cannot be redirected when "externalLinkTarget" is set to "_self" and "routerMode" is set to "history". 
Add new configuration for those cases and completed docs.

Fixes #1046

PR Close #1062