Fix Workhorse linter warnings (part 6)

Problem

make golangci linter detects warnings in following Workhorse files

How to verify

make golangci | grep -E "^internal/api/(block|channel)"

internal/api/block.go:11:1: exported: comment on exported function Block should be of the form "Block ..." (revive)
internal/api/block.go:1:1: ST1000: at least one file in a package should have a package comment (stylecheck)
internal/api/block_test.go:44:4: len: use require.Len (testifylint)
internal/api/block_test.go:61:34: response body must be closed (bodyclose)
internal/api/channel_settings.go:13:6: exported: exported type ChannelSettings should have comment or be unexported (revive)
internal/api/channel_settings.go:19:2: var-naming: struct field Url should be URL (revive)
internal/api/channel_settings.go:1:1: ST1000: at least one file in a package should have a package comment (stylecheck)
internal/api/channel_settings.go:33:1: exported: exported method ChannelSettings.URL should have comment or be unexported (revive)
internal/api/channel_settings.go:37:1: exported: exported method ChannelSettings.Dialer should have comment or be unexported (revive)
internal/api/channel_settings.go:45:29: G402: TLS MinVersion too low. (gosec)
internal/api/channel_settings.go:51:1: exported: exported method ChannelSettings.Clone should have comment or be unexported (revive)
internal/api/channel_settings.go:61:1: exported: exported method ChannelSettings.Dial should have comment or be unexported (revive)
internal/api/channel_settings.go:65:1: exported: exported method ChannelSettings.Validate should have comment or be unexported (revive)
internal/api/channel_settings.go:86:1: exported: exported method ChannelSettings.IsEqual should have comment or be unexported (revive)
internal/api/channel_settings_test.go:107:40: `recognised` is a misspelling of `recognized` (misspell)
internal/api/channel_settings_test.go:114:2: var-naming: don't use underscores in Go names; var chann_header2 should be channHeader2 (revive)
internal/api/channel_settings_test.go:115:2: var-naming: don't use underscores in Go names; var chann_header3 should be channHeader3 (revive)
internal/api/channel_settings_test.go:118:2: var-naming: don't use underscores in Go names; var chann_ca2 should be channCa2 (revive)

Solution

Resolve warnings