CAMEL-21276: camel-core: Lookup ENV variable should use IOHelper to b…

[davsclaus]

…e consistent, and also support camelCase style to have more human readable keys and still match ENV variables that are UPPER_CASE with underscores only.

Description

Target

• I checked that the commit is targeting the correct branch (note that Camel 3 uses camel-3.x, whereas Camel 4 uses the main branch)

Tracking

• If this is a large change, bug fix, or code improvement, I checked there is a JIRA issue filed for the change (usually before you start working on it).

Apache Camel coding standards and style

• I checked that each commit in the pull request has a meaningful subject line and body.

• I have run mvn clean install -DskipTests locally from root folder and I have committed all auto-generated changes.

[github-actions]

🌟 Thank you for your contribution to the Apache Camel project! 🌟

🤖 CI automation will test this PR automatically.

🐫 Apache Camel Committers, please review the following items:

• First-time contributors require MANUAL approval for the GitHub Actions to run

• You can use the command /component-test (camel-)component-name1 (camel-)component-name2.. to request a test from the test bot.

• You can label PRs using build-all, build-dependents, skip-tests and test-dependents to fine-tune the checks executed by this PR.

• Build and test logs are available in the Summary page. Only Apache Camel committers have access to the summary.

• ⚠️ Be careful when sharing logs. Review their contents before sharing them publicly.