garbage collect zero-value UTXOs

[darioAnongba]

Garbage collect the residue zero-value UTXOs when creating transactions. Zero-value UTXOs can occur when creating tombstones or full burns.
Currently, these UTXOs accumulate in the DB and are never cleaned. This PR introduces a garbage collection mechanism in an opportunistic way to collect these UTXOs and use them as inputs of any transaction initiated by tapd:

• Mint
• Burn
• Supply commit
• Funding channels

The mechanism is to select all zero-value UTXOs up to a certain quantity (too avoid exceeding the tx max size).

[coveralls]

Pull Request Test Coverage Report for Build 18227816695

Details

• 63 of 276 (22.83%) changed or added relevant lines in 7 files are covered.
• 27955 unchanged lines in 195 files lost coverage.
• Overall coverage decreased (-15.1%) to 34.578%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
tapfreighter/parcel.go	0	1	0.0%
tapcfg/server.go	0	2	0.0%
tapfreighter/chain_porter.go	0	9	0.0%
tapgarden/planter.go	1	28	3.57%
tapfreighter/wallet.go	60	140	42.86%
tapdb/assets_store.go	1	95	1.05%

Files with Coverage Reduction	New Missed Lines	%
universe/supplyverifier/util.go	1	98.75%
proof/util.go	2	81.63%
tapdb/migrations.go	2	76.06%
tapdb/mssmt.go	2	88.64%
address/log.go	3	0.0%
commitment/log.go	3	0.0%
internal/pedersen/commitment.go	3	95.31%
lndservices/log.go	3	0.0%
rfq/log.go	3	0.0%
tapchannel/log.go	3	0.0%

Totals
Change from base Build 18145713853:	-15.1%
Covered Lines:	30543
Relevant Lines:	88330

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💛 - Coveralls