feat(changelog-tool): add changelog command line tool

.gitignore

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+.idea

Makefile

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+test:
+	rm -rf kong
+	git clone https://github.com/Kong/kong.git
+	rm -f 1.0.0.md
+	echo "# 1.0.0" > 1.0.0.md
+	# use CHANGELOG/unreleased/kong to generate Kong system changelog
+	go build && ./changelog generate --repo Kong/kong --repo_path kong --changelog_path CHANGELOG/unreleased/kong --system Kong >> 1.0.0.md
+	# use CHANGELOG/unreleased/kong to generate Kong-enterprise system changelog
+	go build && ./changelog generate --repo Kong/kong --repo_path kong --changelog_path CHANGELOG/unreleased/kong --system Kong-enterprise >> 1.0.0.md

changelog-markdown.tmpl

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+{{- /* ===== entry template ==== */ -}}
+{{ define "entry" }}
+- {{ $.Message }}
+{{ range $i, $github := $.ParsedGithubs }} [{{ $github.Name }}]({{ $github.Link }}) {{ end }}
+{{ range $i, $jira := $.ParsedJiras }} [{{ $jira.ID }}]({{ $jira.Link }}) {{ end }}
+{{- end }}
+{{- /* ===== entry template ==== */ -}}
+{{- /* ==== section template ==== */ -}}
+{{ define "section"  }}
+{{- if .scopes }}
+{{- $length := len .scopes }}
+{{- if gt $length 0 }}
+### {{ .sectionName }}
+{{ range $i, $scope := .scopes }}
+#### {{ $scope.ScopeName }}
+{{ range $j, $entry := $scope.Entries }} {{ template "entry" $entry }} {{ end }}
+{{ end }}
+{{- end }}
+{{- end }}
+{{- end }}
+{{- /* ==== section template ==== */ -}}
+## {{ .System }}
+{{ template "section" (dict "sectionName" "Performance" "scopes" .Type.performance) }}
+{{ template "section" (dict "sectionName" "Breaking Changes" "scopes" .Type.breaking_change ) }}
+{{ template "section" (dict "sectionName" "Deprecations" "scopes" .Type.deprecation ) }}
+{{ template "section" (dict "sectionName" "Dependencies" "scopes" .Type.dependency ) }}
+{{ template "section" (dict "sectionName" "Features" "scopes" .Type.feature ) }}
+{{ template "section" (dict "sectionName" "Fixes" "scopes" .Type.bugfix ) }}

go.mod

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+module konghq.com/changelog
+
+go 1.20
+
+require (
+	github.com/urfave/cli/v2 v2.25.7
+	gopkg.in/yaml.v3 v3.0.1
+)
+
+require (
+	github.com/cpuguy83/go-md2man/v2 v2.0.2 // indirect
+	github.com/russross/blackfriday/v2 v2.1.0 // indirect
+	github.com/xrash/smetrics v0.0.0-20201216005158-039620a65673 // indirect
+)