[rest libs] Precise Typechecking

[deyaaeldeen]

Packages impacted by this PR

• @azure-rest/confidential-ledger
• @azure-rest/developer-devcenter
• @azure-rest/iot-device-update
• @azure-rest/defender-easm
• @azure-rest/load-testing

Issues associated with this PR

N/A

Describe the problem that is addressed by this PR

Tests are not being typechecked and linting isn't configured correctly. This PR migrates those libraries to precise typechecking setup introduced in #31786

What are the possible designs available to address the problem? If there are more than one possible design, why was the one in this PR chosen?

Are there test cases added in this PR? (If not, why?)

N/A

Provide a list of related PRs (if any)

#31786

Command used to generate this PR:**(Applicable only to SDK release request PRs)

Checklists

• Added impacted package name to the issue description
• Does this PR needs any fixes in the SDK Generator?** (If so, create an Issue in the Autorest/typescript repository and link it here)
• Added a changelog (if necessary)

[azure-sdk]

API change check

API changes are not detected in this pull request.