add Update command to go resource template

[NickElliot]

Unfortunately some major TODOs:

Two functions in terraform.rb need to be converted to a go equivalent. Then logic in the template on one of these functions requires creating a map grouping fields by shared attributes.

• field_specific_update_methods
• properties_by_custom_update
• group_by / key[:]

due to update mask being a nested template, it is not rendering at the moment but should be a smaller addition than the others. there also appears to be an issue where $.UpdateMask is not flagging itself true when it should be based on comparing an output file with one currently in TPG (as dummy text within its block did not render).

Release Note Template for Downstream PRs (will be copied)

[NickElliot]

cc @zli82016

[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

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[modular-magician]

Hi there, I'm the Modular magician. I've detected the following information about your changes:

Diff report

Your PR hasn't generated any diffs, but I'll let you know if a future commit does.