Creates a new flagset to avoid conflit with other libraries that use the same flag

[danimaribeiro]

…the same flag

DataDog/dd-trace-go#1153

❓ What

Baker library conflicts with dd-trace-go library because of dependencies on glog.
glog also defines the flag v
panic: /var/folders/yg/7bk34drs0zjfsb9b_r_1sykr0000gn/T/go-build2940344100/b001/exe/main flag redefined: v

This PR make possible to use both libraries side by side.
It's not possible to send PR to glog because it's a Google internal library that does not accept contributions. But dd-trace-go and also ristretto have dependencies on it.

🔨 How to reproduce the error

Try to import both libraries at the same time:

package main

import (
	"fmt"

	"github.com/AdRoll/baker"
	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
)
func main() {
	tracer.Start(
		tracer.WithEnv("testing"),
		tracer.WithService("tags-automation"),
	)
	defer tracer.Stop()
	components := baker.Components{}
	if err := baker.MainCLI(components); err != nil {
		fmt.Println(err.Error())
	}
}

produces the error:

panic: /var/folders/yn/hdtb3wnd5xg31ygy3vt2g99w0000gn/T/go-build2429850215/b001/exe/testing flag redefined: v

goroutine 1 [running]:
flag.(*FlagSet).Var(0x140000bc120, {0x1059befb8, 0x140004814a8}, {0x1053ac54c, 0x1}, {0x10540798b, 0x1d})
        /usr/local/go/src/flag/flag.go:980 +0x2a4
flag.(*FlagSet).BoolVar(...)
        /usr/local/go/src/flag/flag.go:715
flag.(*FlagSet).Bool(0x0?, {0x1053ac54c, 0x1}, 0x0, {0x10540798b, 0x1d})
        /usr/local/go/src/flag/flag.go:728 +0x70
flag.Bool(...)
        /usr/local/go/src/flag/flag.go:735
github.com/AdRoll/baker.MainCLI({{0x0, 0x0, 0x0}, {0x0, 0x0, 0x0}, {0x0, 0x0, 0x0}, {0x0, ...}, ...})
        /Users/danimar.ribeiro/go/pkg/mod/github.com/!ad!roll/[email protected]/baker_cli.go:35 +0xec
main.main()
        /Users/danimar.ribeiro/Projetos/extra/baker-test/testing.go:17 +0xb4
exit status 2

✅ Checklists

• Have the changes in this PR been functionally tested?
• Has make gofmt-write been run on the code?
• Has make govet been run on the code? Has the code been fixed accordingly to the output?
• Have the changes been added to the CHANGELOG.md file?

[codecov-commenter]

Codecov Report

Merging #213 (d5df4c5) into main (40a57bc) will increase coverage by 7.32%.
The diff coverage is 76.63%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #213      +/-   ##
==========================================
+ Coverage   53.95%   61.28%   +7.32%     
==========================================
  Files          60       67       +7     
  Lines        4003     4972     +969     
==========================================
+ Hits         2160     3047     +887     
- Misses       1646     1687      +41     
- Partials      197      238      +41     

Impacted Files	Coverage Δ
api.go	100.00% <ø> (ø)
baker.go	0.00% <0.00%> (ø)
baker_cli.go	0.00% <0.00%> (ø)
filter/clausefilter.go	73.50% <0.00%> (+1.18%)	⬆️
filter/clear_fields.go	75.00% <0.00%> (+10.71%)	⬆️
filter/dedup.go	90.32% <0.00%> (+1.86%)	⬆️
filter/expand_json.go	96.61% <0.00%> (+0.45%)	⬆️
filter/format_time.go	97.91% <0.00%> (+0.11%)	⬆️
filter/hash.go	77.55% <0.00%> (+0.46%)	⬆️
filter/metadata_lastmodified.go	89.47% <0.00%> (+0.58%)	⬆️
... and 103 more

---

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[arl]

LGTM