[feat] Support multiple sets of search params

[RebootJeff]

e.g., multiple zip codes

[RebootJeff]

v0.4.0 introduced support for multiple cities for searching CVS appointments. A similar approach might be viable for searching multiple zip codes for Walgreens. I.e., the Walgreens checker loops over a list of zip codes and feeds them into a new function that essentially does what the current checker is doing.