add formatting and JSON conversion utilities to ffi

[khieta]

Description of changes

• Adds JSON APIs to apply the policy formatter & convert between the Cedar/JSON formats for policies/schemas
• Removes the corresponding definitions from cedar-wasm/
• Tweaks an error message in the formatter
• Fixes a typo in the wasm build script introduced by Also use macOS to test wasm build in CI #1078. Apparently & is a special character for sed in some positions.

PR to fix downstream breaks in wasm example: cedar-policy/cedar-examples#180

Issue #, if available

Resolves #854

Checklist for requesting a review

The change in this PR is (choose one, and delete the other options):

• A change (breaking or otherwise) that only impacts unreleased or experimental code.

I confirm that this PR (choose one, and delete the other options):

• Updates the "Unreleased" section of the CHANGELOG with a description of my change (required for major/minor version bumps).

I confirm that cedar-spec (choose one, and delete the other options):

• Does not require updates because my change does not impact the Cedar formal model or DRT infrastructure.

[cdisselkoen]

Good note, I had forgotten this was the case in the FFI. It's not true of cedar_policy::Template.

[khieta]

Yeah, I was wondering as I wrote this if we should update the Policy type in the FFI to support both static policies and templates. Opinions? Should we even have a Template type at all?

[cdisselkoen]

Having Policy in the FFI support both static policies and templates might be additionally confusing because Policy in cedar_policy represents both static policies and template-linked policies, but not templates

[khieta]

Yuck. I'll leave it as-is then.

[khieta]

Made an issue #1095