PR# 14859 Various editor/clickable improvements

- Being able to show a tooltip on a.b := g that shows which assigner routine is being called. We called also allow pick and drop on `:=' to go directly on the assigner routine

- Being able to pick and drop a local or argument and go directly to the declaration of that local or argument (or show a tooltip with its declaration)

- Select a local or argument and highlight all the occurrences of it in the body of a routine

- Allow pick and drop of binary and unary operators in text view (currently it only works in flat short)

- Allow pick and drop of the [] operator in text view.