[llvm-pdbutil] Add options to only dump symbol record at specified offset and...

[llvm-pdbutil] Add options to only dump symbol record at specified offset and its parents or children with spcified depth.

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