fix(callFirestore): prevent coercing 0 values (#1039)

[prescottprue]

Description

Original PR here by @michaeldawson: #1039

Created this PR to iron our lint issues and handling of null in an object. Updated tests to include confirming of 0 value

Screenshots (if appropriate)

[codecov]

Codecov Report

Merging #1058 (3beee61) into main (53ee14f) will decrease coverage by 0.09%.
Report is 261 commits behind head on main.
The diff coverage is 87.50%.

@@            Coverage Diff             @@
##             main    #1058      +/-   ##
==========================================
- Coverage   87.27%   87.19%   -0.09%     
==========================================
  Files           6        6              
  Lines         283      289       +6     
  Branches      102      108       +6     
==========================================
+ Hits          247      252       +5     
- Misses         10       11       +1     
  Partials       26       26              

Files Changed	Coverage Δ
src/firebase-utils.ts	83.96% <55.55%> (-0.80%)	⬇️
src/attachCustomCommands.ts	88.15% <100.00%> (ø)
src/extendWithFirebaseConfig.ts	100.00% <100.00%> (ø)
src/plugin.ts	100.00% <100.00%> (ø)
src/tasks.ts	86.90% <100.00%> (+0.65%)	⬆️