Right now, if we want to dump symbol at specified offset, we need to use `grep`.
And it can only show surrounding symbols in layout (not in lexical scope sense).
This adds similar options to `dump` command as `llvm-dwarfdump` to allow users
to dump symbol record at specified offset and its parents or children with
spcified depth.
`--symbol-offset=` must be used with `--modi` to dump only one symbol at given
offset.
`--show-parents`/`--show-children` must be used with `--symbol-offset` to
dump all symbols that are parents/children of the symbol at given offset.
`--parent-recurse-depth`/`--children-recurse-depth` must be used with
`--show-parents`/`--show-children` to specify the max up/down depth.
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D124317
a3b7cb015f