Redo configuration logic

[mayankchhabra]

The PR rewrites the configuration logic to achieve the following:

1. Use templates to generate configuration files for bitcoind, lnd and tor (h/t @lukechilds for the awesome idea).

2. Store RPC + Tor credentials in $UMBREL_ROOT/.env instead of secrets/ directory, allowing us to directly refer them in the Docker services as environment variables vs. having them hardcoded/patched.

3. Reconfigure the installation over and over, even if it fails.

4. OTA updates will now configure a new release as a fresh install with new configuration files and the existing (persistent) data.

5. OTA updates will also pick-up the network (mainnet, testnet or regtest) from the existing .env and configure the new release for it.

6. Commit rpcauth.py to scripts/ so the installation is more deterministic.

7. Generate a different password for Tor instead of using the RPC password.

[lukechilds]

Great stuff!

Some minor tweaks needed which are mostly resolved by this PR: https://github.com/mayankchhabra/umbrel/pull/7

I really love how this gives us a single source of truth for the configuration and we can use to rebuild the actual config files at any point in time.

[lukechilds]

One other suggestion, after running the configure script in an active git repo, you get the following:

$ git status
On branch patch/configure
Your branch is up to date with 'origin/patch/configure'.

Untracked files:
  (use "git add <file>..." to include in what will be committed)

        .env
        bitcoin/bitcoin.conf
        lnd/lnd.conf
        tor/torrc

nothing added to commit but untracked files present (use "git add" to track)

We should add these files to .gitignore so we can develop on an active instance of getumbrel/umbrel without worrying about accidentally committing these files.

It would probably be best to add the entire dirs to .gitignore and then just un-ignore the .gitkeep file inside it.

[lukechilds]

I also really love how docker-compose.yml is just a static file now that inherits everything from the environment.

[mayankchhabra]

Awesome! Thanks for the review and fixes, man.

Also:

It would probably be best to add the entire dirs to .gitignore and then just un-ignore the .gitkeep file inside it.

Great suggestion! Updated.

Looking good to merge :)