[SIEM] Export static functions from top-level module

[rylnd]

The lists plugin is currently reaching deeply into siem to grab some utility functions. They're static so we're good on that front, but if we intend to share these with other plugins we should do that explicitly a la #65247

[elasticmachine]

Pinging @elastic/siem (Team:SIEM)

[rylnd]

This was brought up in a recent linter change: #66588

[FrankHassanabad]

Fixed within #66443