[lldb/crashlog] Make TextCrashLogParser more resilient to new lines

This patch changes the parsing logic for the legacy crash report format
to avoid interrupting the parsing if there are new lines in the middle
of a section.

To do, the parser starts to skip all consecutive empty lines. If the
number of lines skipped is greater than 1, the parser considers that it
reached a new setion of the report and should reset the parsing mode to
back to normal.

Otherwise, it tries to parse the next line in the current parsing mode.
If it succeeds, the parser will also skip that line since it has already
been parsed and continue the parsing.

rdar://107022595

Differential Revision: https://reviews.llvm.org/D157043



Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>