fix(tooltip): properly position tooltips close to container edges
fix(tooltip): properly position tooltips close to container edges

Fixes #1263
Fixes #1371
Closes #1643

ng-bootstrap/core,ng-bootstrap/core,ktriek/ng-bootstrap,ng-bootstrap/ng-bootstrap,mschoudry/ng-bootstrap,maxokorokov/core,maxokorokov/core,ACGC/ng-bootstrap,ACGC/ng-bootstrap,ktriek/ng-bootstrap,fbasso/ng-bootstrap,benouat/ng-bootstrap,ng-bootstrap/ng-bootstrap,Foxandxss/ng-bootstrap,jnizet/ng-bootstrap,mschoudry/ng-bootstrap,jnizet/ng-bootstrap,Foxandxss/ng-bootstrap,chenyuzhcy/ng-bootstrap,benouat/ng-bootstrap,fbasso/ng-bootstrap,Xaiid/ng-bootstrap,Xaiid/ng-bootstrap,ng-bootstrap/ng-bootstrap,Foxandxss/ng-bootstrap,ng-bootstrap/core,jnizet/ng-bootstrap,benouat/ng-bootstrap,mschoudry/ng-bootstrap,chenyuzhcy/ng-bootstrap,ktriek/ng-bootstrap,fbasso/ng-bootstrap,ACGC/ng-bootstrap,pkozlowski-opensource/core,benouat/ng-bootstrap,ktriek/ng-bootstrap,maxokorokov/core,pkozlowski-opensource/core,chenyuzhcy/ng-bootstrap,fbasso/ng-bootstrap,maxokorokov/core,Xaiid/ng-bootstrap,ng-bootstrap/ng-bootstrap,pkozlowski-opensource/core,jnizet/ng-bootstrap