Make SymbolFileDWARF::ParseLineTable use std::sort instead of insertion sort
Motivation: When setting breakpoints in certain projects line sequences are frequently being inserted out of order.
Rather than inserting sequences one at a time into a sorted line table, store all the line sequences as we're building them up and sort and flatten afterwards.
Reviewers: jdoerfert, labath
Reviewed By: labath
Subscribers: teemperor, labath, mgrang, JDevlieghere, lldb-commits
Differential Revision: https://reviews.llvm.org/D72909
(cherry picked from commit 39f1335486eae355b2259d59549382e5cee9e38f)