Fix dokka theme bug with AGP

[thunderbiscuit]

Description

This PR fixes a regression introduced with the upgrade to Android Gradle Plugin 7.1.2, where the Dokka theme applied to the API docs is an older version. I opened an issue on this and they were kind enough to look into it and provide a solution. See Kotlin/dokka#2415

Notes to the reviewers

This is the fix recommended by the Dokka team, which is to apply the Dokka plugin at the root of the project.

All Submissions:

• I've signed all my commits

Bugfixes:

• I'm linking the issue being fixed by this PR

[thunderbiscuit]

FYI I think we're going to get CI checks fails all the time because of the walletTxBuilderDrainWallet() test. Even if we load up the wallet manually when we run our tests locally, running the walletTxBuilderDrainWallet() will keep emptying the wallet, making further CI tests fail.

I think the simplest solution to this is to create a separate wallet for the walletTxBuilderDrainWallet() test. That way we can load up the more often used wallet which is used in the walletTxBuilderBroadcast() test, and the CI will run without problem for long periods of time.

Edit: My proposed fix for this is #51. I have now refilled the test wallet with about 100,000 sats, which should last for just about 100 tests. Happy to send more if the workflow works and we're all happy with it.

[notmandatory]

ACK b8e1282