BLD: add benchmarks for all single-axis indexers

This PR will add benchmarks for all available single-axis container indexing patterns discussed in #6328.

It is currently in WIP state, but the ideas and comments are welcome. Multi-axis indexers are left for future to avoid overcomplicating things from the beginning.

Part of functionality implemented in this ticket is caching `tm.makeCustomIndex` results to avoid spending several seconds in setup of each benchmark. It may deserve a separate PR to implement this caching within `pandas.util.testing` module.