Release v2.0.0-rc.1

[SkymanOne]

The second release candidate:

Changes

• Miscellaneous extrinsics display improvements #916
• Fix decoding of LangError #919
• Upgrade subxt to 0.26 #924
• Display detailed cause of an error #931
• Use package name instead of lib name, default to "rlib" #929

I have to manually update ink! version in Cargo.lock and Cargo.toml because it's release depends on this one.

[ascjones]

Okay, I think we should:

1. Release the contract-build crate from here
2. Update ink_e2e to use this in use-ink/ink#1637
3. Wait for ink v4.0.0-rc to be released
4. Update ink dependencies in this PR
5. Release and merge this PR

Because:

• ink_e2e -> contract-build
• contract-transcode -> ink_env + ink_metadata