feat tooltip: allow to update the tooltip content
feat tooltip: allow to update the tooltip content

Without this fix, when two-way binding "lx-tooltip", the remains
displayed when changing the value of the tooltip.
bright-sparks/lumX,bijeeshtk/lumx,hinablue/lumX,jefvel/lumX,bright-sparks/lumX,hinablue/lumX,cupceavictor/lumX,b-cuts/lumX,bijeeshtk/lumx,terradatum/lumX,ezzye/write-to-be-heard,bright-sparks/lumX,jefvel/lumX,jefvel/lumX,cupceavictor/lumX,terradatum/lumX,cupceavictor/lumX,hinablue/lumX,hinablue/lumX,b-cuts/lumX,b-cuts/lumX,bijeeshtk/lumx,lumapps/lumX,lumapps/lumX,b-cuts/lumX,jefvel/lumX,bijeeshtk/lumx,terradatum/lumX,lumapps/lumX,ezzye/write-to-be-heard,terradatum/lumX,cupceavictor/lumX,ezzye/write-to-be-heard,ezzye/write-to-be-heard,lumapps/lumX,bright-sparks/lumX