Use vfsgen instead of go-bindata (#7080)

* use vfsgen instead of go-bindata

* fix templates

* fix fmt

* vendor vsfgen

vendor/github.com/shurcooL/vfsgen/options.go

@@ -0,0 +1,45 @@
+package vfsgen
+
+import (
+	"fmt"
+	"strings"
+)
+
+// Options for vfsgen code generation.
+type Options struct {
+	// Filename of the generated Go code output (including extension).
+	// If left empty, it defaults to "{{toLower .VariableName}}_vfsdata.go".
+	Filename string
+
+	// PackageName is the name of the package in the generated code.
+	// If left empty, it defaults to "main".
+	PackageName string
+
+	// BuildTags are the optional build tags in the generated code.
+	// The build tags syntax is specified by the go tool.
+	BuildTags string
+
+	// VariableName is the name of the http.FileSystem variable in the generated code.
+	// If left empty, it defaults to "assets".
+	VariableName string
+
+	// VariableComment is the comment of the http.FileSystem variable in the generated code.
+	// If left empty, it defaults to "{{.VariableName}} statically implements the virtual filesystem provided to vfsgen.".
+	VariableComment string
+}
+
+// fillMissing sets default values for mandatory options that are left empty.
+func (opt *Options) fillMissing() {
+	if opt.PackageName == "" {
+		opt.PackageName = "main"
+	}
+	if opt.VariableName == "" {
+		opt.VariableName = "assets"
+	}
+	if opt.Filename == "" {
+		opt.Filename = fmt.Sprintf("%s_vfsdata.go", strings.ToLower(opt.VariableName))
+	}
+	if opt.VariableComment == "" {
+		opt.VariableComment = fmt.Sprintf("%s statically implements the virtual filesystem provided to vfsgen.", opt.VariableName)
+	}
+}