feat: remove go-ipld-format globals

[aschmahmann]

Continuing on #104. These two combined should match ipfs/boxo#322. Happy to have this PR closed and relevant changes made in #104, just needed a usable branch for testing.

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[willscott]

should this use the newer legacy?

[willscott]

i believe the proposal here ended up as part of #104 and this can be closed