chore: onboard @ibm/plex to IBM Telemetry 🚀

[mattrosno]

Adds the config file and dependency necessary to start tracking telemetry data via IBM Telemetry for the packages:

• @ibm/plex

What did you change?

New

• Adds @ibm/telemetry-js dependency
• Adds telemetry.yml config file
• Adds readme telemetry notice
• Adds postinstall script to use the telemetry command
• Adds telemetry.yml as an exported file if the package.json

Changed

• N/A

Removed

• N/A

How did you test and verify your work?

Please look through package.json config files and ensure all necessary modifications have been made so that the "telemetry.yml" config file is included in the release version of each package.

PLEASE NOTE: In order for IBM Telemetry to start collecting data for this project, a new build must be published including these changes.

[mattrosno]

@tay1orjones feel free to defer the review if there are other maintainers to include.

CC @jdharvey-ibm.