Validate that Action inputs do not use reserved params

[evantahler]

An expansion on #1520

This PR also moves calling api.params.buildPostVariables() to the action initializer so can load api.params.globalSafeParams earlier in the boot process.

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Original Description:

issue:
My colleague meets the issue, he adds an "action" key in an action input...
but "action" is a keyword, apiVersion also.
can we have a checker to avoid it? even in build time or runtime.
Example

problem:
I was tried to add class/action.ts validate using api.params.globalSafeParams of initializers/params.ts

But action.validate called by initializers/action.ts and its load priority is 410 and params.ts is 420.
So api.parmas is undefined when action.validate is call.
I was tried to change load priority, but I found params.ts need api.actions two... It's a deadlock, have any idea?