Rename hostRequires_list to host_requires_list
Although it does hold a list of "hostRequires", it's a bit ugly that we end up with a variable that has both mixedCase and snake_case in the same name. So, default to the normal Python convention and use "host_requires_list" for the variable.
However, need to keep hostRequires_list temporarily for compatibility reasons.
Ref. FASTMOVING-1612