[steps] Replace lodash.get with a local helper

[brentvatne]

Why

@expo/steps uses lodash.get@4.4.2, which is deprecated. Its call sites only need the path shapes generated by Steps templates and expression evaluation.

How

• Replace lodash.get with a small local helper.
• Support dot paths, array indices, bracketed keys, quoted keys, nullish traversal, primitive properties, and verbatim own-property precedence.
• Remove lodash.get and @types/lodash.get from the Steps manifest.
• Add focused compatibility coverage for every supported path shape.

Test Plan

• yarn workspace @expo/steps typecheck
• yarn workspace @expo/steps test --runInBand --watchman=false (569 tests)

Stack

1. #4281 — minizlib 3.1.0
2. #4282 — uuid v11
3. #4283 — remove lodash.get
4. #4284 — local-build @expo/bunyan
5. #4285 — prebuild fallback regression tests

This PR depends on #4282.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 64.47%. Comparing base (d029ed7) to head (bfdd522).

Additional details and impacted files

@@                   Coverage Diff                   @@
##           brent/bump-uuid-v11    #4283      +/-   ##
=======================================================
+ Coverage                64.44%   64.47%   +0.03%     
=======================================================
  Files                     1048     1049       +1     
  Lines                    48425    48464      +39     
  Branches                 10203    10213      +10     
=======================================================
+ Hits                     31204    31243      +39     
  Misses                   17105    17105              
  Partials                   116      116              

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[github-actions]

✅ Thank you for adding the changelog entry!