Derek/clk downloads

[betaBison]

Expands file download options to enable downloads for:

• rinex_nav: present - Jan 1, 2013
• sp3 : present - May 24, 2012
• clk : present - Oct 14, 2012
  Also adds secondary sources for WUM0MGXFIN clk, wum clk, and BRDM00DLR_R rinex nav for outlier days when those files weren't uploaded to CDDIS

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6ea032c) 99.62% compared to head (2e1e64e) 99.63%.

Additional details and impacted files

@@            Coverage Diff             @@
##           v0.2.3     #144      +/-   ##
==========================================
+ Coverage   99.62%   99.63%   +0.01%     
==========================================
  Files          21       21              
  Lines        3427     3545     +118     
==========================================
+ Hits         3414     3532     +118     
  Misses         13       13              

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[betaBison]

All downloads were successful on my machine between May 25, 2013 and Nov 6, 2023

[danineamati]

I added a few notes where the comments do not quite match the code. I liked that the order of events in the documentation nicely parallels the code and the tests. The tests check all the relevant date ranges supported in the new branch.

[danineamati]

All feedback addressed!