taskdump: add accessor methods for backtrace (#6975)

spellcheck.dic

@@ -1,4 +1,4 @@
-292
+298
 &
 +
 <
@@ -30,6 +30,8 @@
 450ms
 50ms
 8MB
+ABI
+accessors
 adaptor
 adaptors
 Adaptors
@@ -75,8 +77,11 @@ datagrams
 deallocate
 deallocated
 Deallocates
+debuginfo
 decrementing
+demangled
 dequeued
+dereferenced
 deregister
 deregistered
 deregistering
@@ -133,6 +138,7 @@ implementers
 implementor
 implementors
 incrementing
+inlining
 interoperate
 invariants
 Invariants
@@ -291,4 +297,3 @@ Wakers
 wakeup
 wakeups
 workstealing
-