Remove the Fil+ actors (f06, f07, f080)

[rvagg]

FIP-0118 froze the verified registry (f06), DataCap (f07) and root key holder multisig (f080) at nv29 and said a later upgrade would delete them. This is a proposal for that upgrade.

Nothing on chain can call into these actors any more and we're left with 14 million blocks and 11.8 GB of frozen state, 99% of it the claims table (123M claims across 2,282 provider HAMTs). That's roughly 7.5% of a compressed mainnet snapshot download, included in every splitstore hot store and decoded by every node implementation for no benefit.

A migration would burn the trivial balances (f06 holds ~0.001 FIL, f07 a few nanoFIL, f080 nothing; Lotus already classes f06/f07 as uncirculating so the supply figure is unchanged), deletes the three tree entries, and ships a bundle without the verifiedregistry and datacap types. IDs 6, 7 and 80 are never reused. The historical Fil+ record stays readable at any pre-activation state root, so anyone who wants a convenient export of the final allocation and claim set should take it before activation (the data isn't changing between now and then).

FIP draft posted at: #1301

[rvagg]

One complication to note that I've just discovered. ref-fvm uses an integer mapping of actor codes that comes through iterating https://github.com/filecoin-project/ref-fvm/blob/6d755246c5313bc4a224d6a5bf1445c660e64e8c/fvm/src/machine/manifest.rs#L98, removing actors from the middle will mess that up so we'll have to take care with that.