#4942 refactor/change avellaneda mm reserved to reservation

A description of the changes proposed in the pull request:

The changes stated in #4935 have been performed. Modifications were based on function and member variables renaming over hummingbot/strategy/avellaneda_market_making/avellaneda_market_making.pxd, hummingbot/strategy/avellaneda_market_making/avellaneda_market_making.pyx, and test/hummingbot/strategy/avellaneda_market_making/test_avellaneda_market_making.py.

The documentation was not required for being updated, as it already contains the same terminology as the referred Avellaneda paper.

Tests performed by the developer:

A compilation of the application using ./compile was performed. Added to that, make test has been executed. There were no inconveniences on any of these processes.

Tips for QA testing:

No specific treatment should be done, just ensuring that Avellaneda MM works as expected for QA testing specific cases with this new naming convention.

PR Link: https://github.com/hummingbot/hummingbot/pull/4942