Add csrg mapping format support to chain.py

Temporarily added here until can be moved to srglib
Add full cb<->obf mappings for older versions

Generated with SpecialSource 1.3 snapshot using "-f" flag, to include
even the unrenamed symbols. Useful for working with tools which
haven't yet been updated for processing unrenamed symbols.
Regenerate 1.4.4 cb<->obf with SpecialSource 1.3 snapshot

Missed in past few commits..
Revert "Add csrg mapping format support to chain.py"

No longer needed since will be chaining through non-compact srgs
for now, to include unrenamed symbols in the cross-version mappings.

This reverts commit 25c7e8b83ad54cc372b1ce0dd13d8bfd3a7dabcd.
Add cross-version CB mappings