Add new "MEP" alert code

[trevor229]

As of 8/7/24, the FCC has voted to instate a new EAS alert code of "MEP" for missing/endangered persons. This code is to be used for cases that do not fit the criteria for an AMBER alert or Child Abduction Emergency (CAE).

The new alert code will be available for public safety and law enforcement alert originators to use
within 12 months after the FCC Order establishing the code is published in the Federal Register

I intend to await specification publication before adding this new code to the project. I am unsure of which alert type it will be (possibly just an advisory)

Information can be found here:
https://docs.fcc.gov/public/attachments/DOC-404565A1.pdf
https://docs.fcc.gov/public/attachments/DOC-404576A1.pdf

[trevor229]

Waiting to implement due to uncertainty if the new code will conform to existing EAS standards or modifications are required. I anticipate the MEP alert code to fall under the "advisory" classification in the EAS.