cli: make main command easier to call.

[winder]

Summary

Move the main cobra command into a public cli package.

This makes it easier to embed in another program, see the main.go file for an example.
It also gives finer control over how plugins are selected, as the main function can choose to include or exclude imports.

Test Plan

Existing CI. This is a non functional change that pretty much just moves code around.

Example

In a sample project with a plugin stub, the following is a complete example to recreate the main function for testing:

package main

import (
	"fmt"
	"os"

	_ "github.com/algorand/conduit/conduit/plugins/exporters/all"
	_ "github.com/algorand/conduit/conduit/plugins/importers/all"
	_ "github.com/algorand/conduit/conduit/plugins/processors/all"
	_ "github.com/winder/conduit-test-plugin/plugin" // not published

	"github.com/algorand/conduit/pkg/cli"
)

func main() {
	conduitCmd := cli.MakeConduitCmdWithUtilities()
	if err := conduitCmd.Execute(); err != nil {
		fmt.Fprintf(os.Stderr, "%v\n", err)
		os.Exit(1)
	}
	os.Exit(0)
}

go.mod

module github.com/winder/conduit-test-plugin

go 1.17

require (
	github.com/algorand/conduit v1.1.0
	github.com/algorand/go-algorand-sdk/v2 v2.0.0-20230324200319-055c8d2b174a
	github.com/sirupsen/logrus v1.8.1
	github.com/spf13/cobra v1.3.0 // indirect
	gopkg.in/yaml.v2 v2.4.0
)

// redirect to this branch
replace github.com/algorand/conduit => github.com/winder/conduit v0.0.0-20230505131953-c8c6d92fd0f9

> go run cmd/main.go list 
importers:
  algod       - Importer for fetching blocks from an algod REST API.
  file_reader - Importer for fetching blocks from files in a directory created by the 'file_writer' plugin.

processors:
  filter_processor - Filter transactions out of the results according to a configurable pattern.
  noop             - noop processor

exporters:
  file_writer - Exporter for writing data to a file.
  test_plugin - Local plugin included along with the others.
  noop        - noop exporter
  postgresql  - Exporter for writing data to a postgresql instance.

[codecov]

Codecov Report

Merging #71 (c8c6d92) into master (442791a) will increase coverage by 0.84%.
The diff coverage is 73.46%.

@@            Coverage Diff             @@
##           master      #71      +/-   ##
==========================================
+ Coverage   67.66%   68.50%   +0.84%     
==========================================
  Files          32       36       +4     
  Lines        1976     2388     +412     
==========================================
+ Hits         1337     1636     +299     
- Misses        570      660      +90     
- Partials       69       92      +23     

Impacted Files	Coverage Δ
conduit/data/block_export_data.go	100.00% <ø> (+92.30%)	⬆️
conduit/plugins/importers/algod/metrics.go	100.00% <ø> (ø)
pkg/cli/internal/list/list.go	20.75% <ø> (ø)
...lugins/exporters/postgresql/postgresql_exporter.go	66.66% <51.21%> (-11.54%)	⬇️
pkg/cli/cli.go	65.97% <65.97%> (ø)
conduit/pipeline/pipeline.go	66.09% <72.10%> (+0.64%)	⬆️
conduit/data/config.go	76.47% <76.47%> (ø)
conduit/plugins/importers/algod/algod_importer.go	84.69% <88.17%> (-3.62%)	⬇️
conduit/pipeline/errors.go	100.00% <100.00%> (ø)
pkg/cli/internal/initialize/init.go	75.00% <100.00%> (ø)

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[tzaffi]

Verified by building the conduit binary and checking its version command.