Fork channel

Create a new channel as a copy of main.

Rename channel

Rename main to:

Delete channel

Delete main? This cannot be undone.

test-3.test
# RUN: obj2yaml %S/Inputs/test-3.o | yaml2obj -o %t.o
# RUN: llvm-pdbutil dump --types %t.o | FileCheck %s -check-prefix=ALL

# ALL: {{.*}} guid = {A03206E7-6691-415E-A241-0B5A0D0EE37A}