fix(configuration): improve environment variable substitution to handle all the cases shown in the spec

[trentm]

https://opentelemetry.io/docs/specs/otel/configuration/data-model/#environment-variable-substitution
provides a number of test cases to exercise the algorithm expected
for environment variable substitution. This adds those test cases
and updates the processing to handle them all.

[codecov]

Codecov Report

❌ Patch coverage is 97.82609% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 94.92%. Comparing base (8e4d4ed) to head (ddf8b6c).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
experimental/packages/configuration/src/utils.ts	97.61%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6757      +/-   ##
==========================================
- Coverage   94.92%   94.92%   -0.01%     
==========================================
  Files         377      377              
  Lines       12818    12827       +9     
  Branches     2924     2920       -4     
==========================================
+ Hits        12168    12176       +8     
- Misses        650      651       +1     

Files with missing lines	Coverage Δ
...al/packages/configuration/src/FileConfigFactory.ts	98.16% <100.00%> (-0.27%)	⬇️
experimental/packages/configuration/src/utils.ts	97.43% <97.61%> (-0.61%)	⬇️

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[trentm]

Before this change, the env var substitution was failing these added tests:

    substituteEnvVars
      ✔ key: ${STRING_VALUE}
      ✔ key: ${BOOL_VALUE}
      ✔ key: ${INT_VALUE}
      ✔ key: ${FLOAT_VALUE}
      1) key: ${HEX_VALUE}
      ✔ key: "${STRING_VALUE}"
      2) key: "${BOOL_VALUE}"
      3) key: "${INT_VALUE}"
      4) key: "${FLOAT_VALUE}"
      ✔ key: "${HEX_VALUE}"
      ✔ key: "${env:STRING_VALUE}"
      ✔ key: "${INVALID_MAP_VALUE}"
      ✔ key: foo ${STRING_VALUE} ${FLOAT_VALUE}
      ✔ key: ${UNDEFINED_KEY}
      ✔ key: ${UNDEFINED_KEY:-fallback}
      ✔ ${STRING_VALUE}: value
      ✔ key: ${REPLACE_ME}
      ✔ key: ${UNDEFINED_KEY:-${STRING_VALUE}}
      5) key: ${STRING_VALUE:?error}
      ✔ key: $${STRING_VALUE}
      ✔ key: $$${STRING_VALUE}
      ✔ key: $$$${STRING_VALUE}
      ✔ key: $${STRING_VALUE:-fallback}
      ✔ key: $${STRING_VALUE:-${STRING_VALUE}}
      6) key: ${UNDEFINED_KEY:-$${UNDEFINED_KEY}}
      ✔ key: ${VALUE_WITH_ESCAPE}
      ✔ key: a $$ b
      ✔ key: a $ b

and others not in the set of examples in the spec, like FOO=TRUE (YAML allows a few capitalizations of bools),
other number forms (e.g. .1, 1e6, octal, etc.)