bootnode version fix

[dimalinux]

daemon_version RPC requests on the bootnode where causing it to crash. It was accessing the protocolBackend interface, which is nil for bootnodes to get the chain-ID as well as the contract address. We also had Prometheus metrics that were added that were accessing protocolBackend.

Implemented solutions:

• We now get the chain-ID from the environment for daemon_version. We verify that the chain-ID matches the environment on start, so this should always be accurate.
• Bootnodes do not report a contract address in the version response. swapd instances report the contract address in the version because they can change it. Bootnodes never access the contract, so it makes sense for them to just omit the value.
• Prometheus stats are not started for bootnodes. If we want some stats for bootnodes in the future, we'll need to add them in a separate PR.
• Bootnodes were integrated into the integration tests, and some unit tests, so we don't run into this issue again. The new tests immediately caught the issue with the Prometheus stats.
• Since the integration test startup script was getting a partial rewrite, I removed our dependency on the contract-addresses.json closing an extra ticket from the backlog.

Closes #465 Closes #202

[codecov[bot]]

Codecov Report

Patch coverage: 90.16% and project coverage change: +0.36 :tada:

Comparison is base (3859162) 57.57% compared to head (7490c90) 57.94%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #467 +/- ## ========================================== + Coverage 57.57% 57.94% +0.36% ========================================== Files 125 127 +2 Lines 12008 12185 +177 ========================================== + Hits 6914 7060 +146 - Misses 4361 4381 +20 - Partials 733 744 +11 ``` | [Impacted Files](https://app.codecov.io/gh/AthanorLabs/atomic-swap/pull/467?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | Coverage Δ | | |---|---|---| | [cmd/swapd/main.go](https://app.codecov.io/gh/AthanorLabs/atomic-swap/pull/467?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-Y21kL3N3YXBkL21haW4uZ28=) | `66.05% <ø> (-0.09%)` | :arrow_down: | | [common/config.go](https://app.codecov.io/gh/AthanorLabs/atomic-swap/pull/467?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-Y29tbW9uL2NvbmZpZy5nbw==) | `81.81% <68.42%> (-4.15%)` | :arrow_down: | | [bootnode/bootnode.go](https://app.codecov.io/gh/AthanorLabs/atomic-swap/pull/467?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-Ym9vdG5vZGUvYm9vdG5vZGUuZ28=) | `66.00% <100.00%> (ø)` | | | [cmd/bootnode/main.go](https://app.codecov.io/gh/AthanorLabs/atomic-swap/pull/467?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-Y21kL2Jvb3Rub2RlL21haW4uZ28=) | `66.66% <100.00%> (ø)` | | | [cmd/swapd/contract.go](https://app.codecov.io/gh/AthanorLabs/atomic-swap/pull/467?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-Y21kL3N3YXBkL2NvbnRyYWN0Lmdv) | `55.17% <100.00%> (-1.65%)` | :arrow_down: | | [daemon/swap\_daemon.go](https://app.codecov.io/gh/AthanorLabs/atomic-swap/pull/467?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-ZGFlbW9uL3N3YXBfZGFlbW9uLmdv) | `66.36% <100.00%> (+0.30%)` | :arrow_up: | | [rpc/daemon.go](https://app.codecov.io/gh/AthanorLabs/atomic-swap/pull/467?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-cnBjL2RhZW1vbi5nbw==) | `100.00% <100.00%> (ø)` | | | [rpc/server.go](https://app.codecov.io/gh/AthanorLabs/atomic-swap/pull/467?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-cnBjL3NlcnZlci5nbw==) | `75.96% <100.00%> (+1.58%)` | :arrow_up: | ... and [7 files with indirect coverage changes](https://app.codecov.io/gh/AthanorLabs/atomic-swap/pull/467/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None)

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