[FEA] Replace internal usage of std::string with std::string_view

[vyasr]

Is your feature request related to a problem? Please describe. There are currently a number of libcudf functions that accept a std::string argument when they don't need to own the string but could simply use a view. Others take a const ref to a std::string, explicitly indicating that they don't require ownership. These include:

• https://github.com/rapidsai/cudf/blob/ce247961216dd70f389763dc086f137c11ad7346/cpp/include/cudf/aggregation.hpp#L559
• https://github.com/rapidsai/cudf/blob/ce247961216dd70f389763dc086f137c11ad7346/cpp/include/cudf/interop.hpp#L107
• https://github.com/rapidsai/cudf/blob/ce247961216dd70f389763dc086f137c11ad7346/cpp/include/cudf/io/types.hpp#L210 (multiple in this file)
• https://github.com/rapidsai/cudf/blob/ce247961216dd70f389763dc086f137c11ad7346/cpp/include/cudf/io/json.hpp#L386 (multiple in this file, and also all other I/O format files like csv.hpp)

There may be others as well.

Describe the solution you'd like We should do a thorough audit of std::string usage in libcudf to ensure that we are properly using std::string_view instead where appropriate.

Additional context A subset of this request was originally documented in https://github.com/rapidsai/cudf/issues/14413, which indicates that some of these changes may be nontrivial to implement.

[karthikeyann]

Line 386 in json.hpp is std::map of std::string. string_view can not be used here because the string_view's underlying string may get invalidated and the string_view will still point to destroyed/modified object memory.

[karthikeyann]

source_info constructor could be updated to take string_view https://github.com/rapidsai/cudf/blob/branch-24.08/cpp/include/cudf/io/types.hpp#L338 It's common for many readers