Split SQLite Wallet into separate package

[devhawk]

As per #2678, the EF + SQLite dependency bloats the uncompressed size of Neo.dll + depenencies (as generated by dotnet publish) by 5x (28MB vs 6.2MB). Initial test of compressed package size shows a 60% reduction (17.6MB vs 7MB for Neo.Compiler.CSharp compressed nuget package).

EF + SQLite are only used for legacy UserWallet. GIven the significant size bloat this dependency add and the relatively low usage pattern for UserWallet, it seems worth it to move UserWallet to a separate package. Tools + libraries that don't need UserWallet support (Neo.Compiler.CSharp, Neo Debugger, Neo Blockchain Library) see a significant size reduction while tools and libraries that do need UserWallet support (RpcServer, NeoCli, NeoGui, NeoExpress) can continue to get that support by adding the new package dependency.

cc @erikzhang @shargon
fixes #2678

[erikzhang]

I think it should be moved to a plugin.

[devhawk]

I think it should be moved to a plugin.

I think that's a good idea - as suggested by @Liaojinghui and tracked by #2564 - but I don't think we have enough time to make a change that fundamental before releasing v3.2.

The change in this PR is a simple packaging one. Packages that don't use UserWallet like NCCS make no change but get >50% space savings. Packages that do use UserWallet (RpcServer, NeoCli) only have to add a single package dependency and have all the same functionality they have today.

Can we merge this PR now, realize the package size savings for the v3.2 release and work on a new wallet abstraction + module for v3.3?

[erikzhang]

It cannot be merged because it creates sqlite-wallet. I don't think it's necessary to create an extra package.

[devhawk]

It cannot be merged because it creates sqlite-wallet. I don't think it's necessary to create an extra package.

@erikzhang Would you support removing SQLite wallet support from neo.dll completely? We could move the UserWallet code to neo-cli so users can still migrate SQLite wallets. I actually like that approach better because it would also remove the SQLite dependency from RpcServer