Add in the Regal Linter for OPA Rego

[amart241]

One of the OPA maintainers came back on the M365 side and did all of the work in a PR needed to make the OPA linter work for us. This epic is to make updates to our Rego code for all products to adhere to those OPA linter rules.

• Gmail
• Google Calendar
• Groups
• Google Chat
• Google Drive & Docs
• Google Meet
• Google Sites
• Common Controls
• Rules
• Google Classroom

See Common Controls Rego for an example

• Refactor long line within the 120 character limit set by Regal (https://docs.styra.com/opa/rego-style-guide#keep-line-length--120-characters)
• Removed trailing whitespace.
• Refactor most lists to sets (per https://docs.styra.com/opa/rego-style-guide#prefer-sets-over-arrays-where-applicable)
• Refactor rule syntax to contains (https://www.openpolicyagent.org/docs/latest/policy-language/#generating-sets)
• Remove zero-arity functions (such as GetTopLevelOU, see https://docs.styra.com/regal/rules/bugs/zero-arity-function)
• Switche to some iteration (https://docs.styra.com/regal/rules/style/prefer-some-in-iteration)
• Use equals pattern matching when applicable (https://docs.styra.com/regal/rules/idiomatic/equals-pattern-matching)
• Remove constant conditions (https://docs.styra.com/regal/rules/bugs/constant-condition), specifically for the not-implemented rules.
• Change the or list comprehensions to true in Conditions (Deprecation of any and all affects gatekeeper-library policies open-policy-agent/gatekeeper-library#225 (comment))
• Change the 'and' list comprehensions to (false in Conditions) == false

[buidav]

Duplicate of #69