Issue667 - Add global_data_tags to fleet agent policies

[Zyther]

Whew.

Picking up from where @mholttech left off, this implements global data tags on the agent policy resource.

This change:

• implements Issue 667
• Modifies CRUD of agent policies to include a global_data_tags block, if it exists
• asks for a nested attribute object at the hcl/tf resource level
• updates kibana.gen.go to 3757e641278a5186919e35a0f980ac3cda7e8ccd
• links the global data tags schemas together (post, put, get) so they can be used to marshal/unmarshal universally

Thanks! Let me know what else is needed.

[cla-checker-service]

💚 CLA has been signed

[Zyther]

oi, need to fix this. apologies

[tobio]

Looking great! A couple of small changes before we can get this merged.

[Zyther]

All set! :)