mir-borrowck: Add method to MIR borrowck context to retrieve the span of a given borrow
mir-borrowck: Add method to MIR borrowck context to retrieve the span of a given borrow

graydon/rust,graydon/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,aidancully/rust,aidancully/rust,GBGamer/rust,graydon/rust,graydon/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,graydon/rust,aidancully/rust,GBGamer/rust,graydon/rust,GBGamer/rust,aidancully/rust