@truffle/db Option to save .db directory to project directory

[tenthirtyone]

Summary

Adds the saveLocally property to the db section of the truffle-config.js

db: {
      enabled: true,
      saveLocally: true,      
    },

When enabled, the db adapters will return the working directory as the location to save the .db folder.

To Test

1. Enable the db flag above in your truffle-config.js.
2. I tested using db-kit, it's enough to just start the application.

ER: .db directory exists in ~/.config/truffle-nodejs/ (@truffle/config getTruffleDataDirectory())

3. Bomb out of db-kit (ctrl-c)
4. Enable the saveLocally config flag above with the already enabled db flag.
5. Start db-kit

ER: .db directory exists in your truffle project directory (@truffle/config detect().working_directory)

Closes #4495

[gnidan]

It looks like this PR modifies the project-level config, where we ideally want to save users the trouble of configuring this on a per-project basis... instead I think we want this to be a user-level config option. Happy to explain more in our next call.

[gnidan]

few minor things. thanks for taking this on!

[gnidan]

This shouldn't be in this example anymore, since we've moved this option from truffle-config over to the user-level config

[cds-amal]

saveLocally is ambiguous. Would you consider db.saveToProjectRoot?

[tenthirtyone]

@cds-amal You got it, thanks for taking a look.

[gnidan]

Looks good! Just one remaining comment about the README. Thanks @tenthirtyone!

[gnidan]

So there's some infrastructure for doing this automatically via truffle config set <...>. I forget the exact syntax; @eggplantzzz or @cds-amal do you remember offhand?

In any event, we probably want to recommend that approach rather than forcing users to find this file and edit it manually - since the path differs based on OS (Mac will use ~/Library/Application\ Support/truffle-nodejs, for instance)

[tenthirtyone]

Oh fantastic.

I wasn't aware of the convenience command. I can probably drill down - packages/core/lib/commands/config.js (but wouldn't mind the exact syntax).

[cds-amal]

Unfortunately the infrastructure isn't quite there yet

[gnidan]

Maybe we need to do a separate PR to get this TODO addressed, and then rebase this once that's merged?

[tenthirtyone]

I can jump over to tackle it since it's all connected.

[tenthirtyone]

Closing and making it part of #4680