[Uptime] Require type check object for API requests

[justinkambic]

Describe the feature:
As noted in #59881 (comment) - we could provide runtime checking and automatic type population for all of our gets.

As part of #59881, we are providing an optional parameter so callers can supply an io-ts object that implements the Decoder interface, which will be used to parse the response and log an error if the type does not correspond to the data.

To resolve this issue, that decoder parameter should become required, and all calling code will provide a type decoder when it makes API requests.

Describe a specific use case for the feature:
Today in Uptime, all of our API responses are essentially unchecked any, and it's been up to the calling code to perform validation themselves.

With this change, we would provide type decoders for all existing API requests, and any new ones would be required to implement a validator as part of their changes. This will give us better runtime stability, and make a nicer development experience because we will have increased reliance on static typing.

[elasticmachine]

Pinging @elastic/uptime (Team:uptime)