config: update precache using main/4.21-RC response (#187)

Updates precache to output from a CloudStack repo main branch/4.21 env.
Some API/param descriptions now contain backticks, which break the format in precache.go.
Therefore, instead of adding listApis output as a string variable, store the output in a JSON file and use embed to get it in a Go variable.

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Signed-off-by: Abhishek Kumar <[email protected]>

Author: shwstppr