Support MSP_BIZ rate plan

[ch0wm3in]

As the title says, support the rate plan called MSP_BIZ

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[ch0wm3in]

resource/cloudflare_zone: Add MSP_BIZ rate plan as supported parameter for `plan` .

[jacobbednarz]

thanks for the PR! unfortunately this isn't a publicly documented subscription nor is the internal/external plan mapping correct so at this point, we cannot accept it without having the public API contract established.

for now, I will make this as pending documentation and I'd recommend submitting a support ticket to get this documented so we can accept it here.

[ch0wm3in]

@jacobbednarz Any news regarding this?