Migrate to Synapse 2.0 (post 202608 FWSS mainnet upgrade)

[BigLep]

Synapse 2.0 ships immediately after the [Tracking Issue] 202608 FOC Release (FilOzone/filecoin-services#597) and removes the piece-metadata getters that filecoin-pin currently depends on.

Scope:

• Bump @filoz/synapse-sdk to ^2.0.0 and @filoz/synapse-core accordingly once released in chore(master): release synapse-sdk 2.0.0 FilOzone/synapse-sdk#942

Depends on:

• Update to latest Synapse release (synapse-sdk@1.2.1) #684 (update to latest Synapse release)
• Stop exposing piece metadata (filecoin-project/filecoin-pin#668) is already out for PR and can land independently/beforehand. This issue is specifically about the dependency bump to 2.0 and validating against the post-upgrade contracts. It depends on that removal work being completed.
• the FWSS mainnet contract upgrade / Synapse 2.0 release.

[BigLep]

@silent-cipher : I'm assigning this to you assuming you're helping with 202608 release related work.