fix: allow extendTo to be 0 in ExtendFootprintTTLOperation

[overcat]

extendTo is a uint32 and 0 is a valid value, but the builder validation rejected it with extendTo <= 0.

Fixes #810

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.95%. Comparing base (3836471) to head (4c7983d).

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #811      +/-   ##
============================================
+ Coverage     82.91%   82.95%   +0.03%     
  Complexity     1661     1661              
============================================
  Files           232      232              
  Lines          6047     6047              
  Branches        677      677              
============================================
+ Hits           5014     5016       +2     
+ Misses          656      654       -2     
  Partials        377      377              

Files with missing lines	Coverage Δ
...ar/sdk/operations/ExtendFootprintTTLOperation.java	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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