Add two time-trace scope variables.

A time trace scope variable of `ParseDeclarationOrFunctionDefinition`
with the function's source location is added to record the time spent
parsing the function's declaration or definition. Another time trace
scope variable of `ParseFunctionDefinition` is also added to record the
name of the defined function. A release note is added as well.

Reviewed by: Aaron Ballman
Pull request: #65268