[CHIA-292] Modify VerifiedCredential.launch to handle multiple source coins

[Quexington]

Previously there was a bug where launching a VC with multiple coins (assuming you need a fee for example) would ail due to the driver's expectation that there would be only one. The patch modifies that driver to support multiple source coins.

[coveralls-official]

Pull Request Test Coverage Report for Build 9005501291

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 13 of 13 (100.0%) changed or added relevant lines in 3 files are covered.
• 31 unchanged lines in 9 files lost coverage.
• Overall coverage decreased (-0.02%) to 90.805%

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Files with Coverage Reduction	New Missed Lines	%
chia/full_node/full_node_api.py	1	81.0%
chia/timelord/timelord_launcher.py	1	69.92%
chia/introducer/introducer.py	1	78.26%
chia/data_layer/data_store.py	2	95.39%
chia/data_layer/data_layer_wallet.py	2	91.15%
chia/data_layer/data_layer.py	3	85.26%
chia/server/node_discovery.py	4	80.5%
chia/wallet/wallet_node.py	7	88.51%
chia/full_node/full_node.py	10	85.19%

Totals
Change from base Build 9002628913:	-0.02%
Covered Lines:	98874
Relevant Lines:	108828

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💛 - Coveralls

[wjblanke]

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