check for mongo extension

[brettmc]

if platform requirements are ignored, then trying to load this module causes a fatal error. that's particularly bad because it happens during composer autoloading, so add an extra check and do not try to run without the extension.

[codecov]

Codecov Report

Merging #194 (496bd72) into main (c8e79a8) will increase coverage by 6.26%.
Report is 2 commits behind head on main.
The diff coverage is 92.30%.

❗ Current head 496bd72 differs from pull request most recent head 7fd2cb1. Consider uploading reports for the commit 7fd2cb1 to get more accurate results

@@             Coverage Diff              @@
##               main     #194      +/-   ##
============================================
+ Coverage     28.60%   34.86%   +6.26%     
- Complexity      472      816     +344     
============================================
  Files            47       71      +24     
  Lines          1755     3086    +1331     
============================================
+ Hits            502     1076     +574     
- Misses         1253     2010     +757     

Flag	Coverage Δ
7.4	46.34% <92.30%> (-5.96%)	⬇️
8.0	34.94% <92.30%> (+7.07%)	⬆️
8.1	34.97% <92.30%> (+7.04%)	⬆️
8.2	34.81% <92.30%> (+6.19%)	⬆️

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Files Changed	Coverage
src/ResourceDetectors/Container/src/Container.php	92.30%

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