Make the project multi-modules

[pm47]

Instead of using a root project, using https://github.com/Kotlin/kotlinx-io project as reference.

Using modules allows a finer control of classes visibility and will be especially useful for a future db module containing a default sqldelight implementation (see sqldelight/sqldelight#1333 (comment)).

⚠️ Merging this PR will create conflicts in all other PRs due to moving the src directory.

[dpad85]

The project now publishes a Maven artifact under artifact id lightning-kmp-core instead of lightning-kmp, which affects dependant projects.

We could copy eclair, with publishes a top-level eclair module and also several artifacts like eclair-core or eclair-node. So we'd have:

• lightning-kmp root project
• lightning-kmp-core module
• lightning-kmp-db module

If you only need the core dependency, you would run ./gradlew :lightning-kmp-core:publishToMavenLocal. If you need core+db, you run ./gradlew publishToMavenLocal. Not quite sure how to do make this happen in gradle though.

Another option could be to modify the MavenPublication task and rename the lightning-kmp-core Maven artifact to lightning-kmp, so that we keep the same id as before.

[sstone]

modules branch should be renamed to snapshot/modules. This will trigger our publishing workflow on github Actions and will let us publish snapshot versions to https://oss.sonatype.org/content/repositories/snapshots/ (our publishing scripts will probably need to be updated too) so we can also test that downstream projects (phoenix, phoenixd) can still be built properly.

[pm47]

modules branch should be renamed to snapshot/modules. This will trigger our publishing workflow on github Actions and will let us publish snapshot versions to https://oss.sonatype.org/content/repositories/snapshots/ (our publishing scripts will probably need to be updated too) so we can also test that downstream projects (phoenix, phoenixd) can still be built properly.

True but CI takes a long time to build...

[pm47]

We could copy eclair, with publishes a top-level eclair module and also several artifacts like eclair-core or eclair-node.

Actually, linking the root eclair project will not pull all child dependencies. We could try to do that on lightning-kmp, but I'm not sure it's worth it.