[Request-evaluator] Add PrettyStackTrace support.
[Request-evaluator] Add PrettyStackTrace support.

Print out the stack of requests being evaluated when we crash, so we can see
the dependency chain the triggered the crash.

parkera/swift,glessard/swift,harlanhaskins/swift,roambotics/swift,shajrawi/swift,apple/swift,gregomni/swift,sschiau/swift,natecook1000/swift,JGiola/swift,jckarter/swift,gregomni/swift,jmgc/swift,harlanhaskins/swift,xwu/swift,shahmishal/swift,rudkx/swift,xedin/swift,jckarter/swift,sschiau/swift,lorentey/swift,shajrawi/swift,brentdax/swift,devincoughlin/swift,danielmartin/swift,shajrawi/swift,amraboelela/swift,stephentyrone/swift,shahmishal/swift,danielmartin/swift,lorentey/swift,jopamer/swift,stephentyrone/swift,allevato/swift,CodaFi/swift,rudkx/swift,aschwaighofer/swift,shahmishal/swift,harlanhaskins/swift,sschiau/swift,aschwaighofer/swift,glessard/swift,austinzheng/swift,nathawes/swift,stephentyrone/swift,roambotics/swift,practicalswift/swift,gribozavr/swift,shahmishal/swift,gribozavr/swift,xedin/swift,xwu/swift,harlanhaskins/swift,karwa/swift,rudkx/swift,natecook1000/swift,apple/swift,stephentyrone/swift,gregomni/swift,allevato/swift,sschiau/swift,austinzheng/swift,ahoppen/swift,nathawes/swift,harlanhaskins/swift,aschwaighofer/swift,xwu/swift,alblue/swift,apple/swift,roambotics/swift,atrick/swift,danielmartin/swift,amraboelela/swift,austinzheng/swift,jmgc/swift,jopamer/swift,hooman/swift,devincoughlin/swift,parkera/swift,xedin/swift,tkremenek/swift,alblue/swift,apple/swift,amraboelela/swift,danielmartin/swift,xedin/swift,lorentey/swift,jopamer/swift,hooman/swift,aschwaighofer/swift,nathawes/swift,ahoppen/swift,alblue/swift,benlangmuir/swift,nathawes/swift,aschwaighofer/swift,stephentyrone/swift,CodaFi/swift,devincoughlin/swift,shajrawi/swift,allevato/swift,gregomni/swift,allevato/swift,roambotics/swift,benlangmuir/swift,xedin/swift,alblue/swift,ahoppen/swift,xwu/swift,rudkx/swift,CodaFi/swift,airspeedswift/swift,amraboelela/swift,sschiau/swift,JGiola/swift,JGiola/swift,tkremenek/swift,CodaFi/swift,jckarter/swift,harlanhaskins/swift,xedin/swift,devincoughlin/swift,natecook1000/swift,practicalswift/swift,rudkx/swift,JGiola/swift,nathawes/swift,practicalswift/swift,practicalswift/swift,gribozavr/swift,xedin/swift,shahmishal/swift,aschwaighofer/swift,shajrawi/swift,natecook1000/swift,roambotics/swift,CodaFi/swift,nathawes/swift,atrick/swift,austinzheng/swift,stephentyrone/swift,devincoughlin/swift,practicalswift/swift,JGiola/swift,brentdax/swift,jmgc/swift,glessard/swift,aschwaighofer/swift,brentdax/swift,JGiola/swift,jckarter/swift,nathawes/swift,gribozavr/swift,alblue/swift,apple/swift,lorentey/swift,karwa/swift,practicalswift/swift,amraboelela/swift,karwa/swift,benlangmuir/swift,lorentey/swift,karwa/swift,shajrawi/swift,jmgc/swift,harlanhaskins/swift,danielmartin/swift,lorentey/swift,airspeedswift/swift,hooman/swift,tkremenek/swift,lorentey/swift,devincoughlin/swift,xwu/swift,karwa/swift,jopamer/swift,airspeedswift/swift,stephentyrone/swift,shajrawi/swift,amraboelela/swift,practicalswift/swift,atrick/swift,atrick/swift,glessard/swift,sschiau/swift,devincoughlin/swift,natecook1000/swift,shahmishal/swift,rudkx/swift,gribozavr/swift,brentdax/swift,gribozavr/swift,austinzheng/swift,karwa/swift,hooman/swift,jmgc/swift,gribozavr/swift,parkera/swift,jopamer/swift,parkera/swift,sschiau/swift,hooman/swift,hooman/swift,jmgc/swift,tkremenek/swift,shahmishal/swift,karwa/swift,apple/swift,jopamer/swift,brentdax/swift,ahoppen/swift,sschiau/swift,allevato/swift,jmgc/swift,shahmishal/swift,gribozavr/swift,jckarter/swift,xwu/swift,danielmartin/swift,natecook1000/swift,airspeedswift/swift,austinzheng/swift,airspeedswift/swift,airspeedswift/swift,jckarter/swift,parkera/swift,xedin/swift,benlangmuir/swift,lorentey/swift,ahoppen/swift,atrick/swift,hooman/swift,allevato/swift,allevato/swift,gregomni/swift,benlangmuir/swift,CodaFi/swift,austinzheng/swift,alblue/swift,brentdax/swift,shajrawi/swift,brentdax/swift,atrick/swift,glessard/swift,glessard/swift,xwu/swift,jopamer/swift,parkera/swift,karwa/swift,gregomni/swift,CodaFi/swift,benlangmuir/swift,jckarter/swift,tkremenek/swift,devincoughlin/swift,alblue/swift,amraboelela/swift,airspeedswift/swift,parkera/swift,tkremenek/swift,tkremenek/swift,practicalswift/swift,roambotics/swift,danielmartin/swift,parkera/swift,natecook1000/swift,ahoppen/swift