Add SPA UI for GARM

This change adds a single page application front-end to GARM. It uses
a generated REST client, built from the swagger definitions, the websocket
interface for live updates of entities and eager loading of everything
except runners, as users may have many runners and we don't want to load
hundreds of runners in memory.

Proper pagination should be implemented in the API, in future commits,
to avoid loading lots of elements for no reason.

Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>

vendor/github.com/spf13/pflag/errors.go

@@ -0,0 +1,149 @@
+package pflag
+
+import "fmt"
+
+// notExistErrorMessageType specifies which flavor of "flag does not exist"
+// is printed by NotExistError. This allows the related errors to be grouped
+// under a single NotExistError struct without making a breaking change to
+// the error message text.
+type notExistErrorMessageType int
+
+const (
+	flagNotExistMessage notExistErrorMessageType = iota
+	flagNotDefinedMessage
+	flagNoSuchFlagMessage
+	flagUnknownFlagMessage
+	flagUnknownShorthandFlagMessage
+)
+
+// NotExistError is the error returned when trying to access a flag that
+// does not exist in the FlagSet.
+type NotExistError struct {
+	name                string
+	specifiedShorthands string
+	messageType         notExistErrorMessageType
+}
+
+// Error implements error.
+func (e *NotExistError) Error() string {
+	switch e.messageType {
+	case flagNotExistMessage:
+		return fmt.Sprintf("flag %q does not exist", e.name)
+
+	case flagNotDefinedMessage:
+		return fmt.Sprintf("flag accessed but not defined: %s", e.name)
+
+	case flagNoSuchFlagMessage:
+		return fmt.Sprintf("no such flag -%v", e.name)
+
+	case flagUnknownFlagMessage:
+		return fmt.Sprintf("unknown flag: --%s", e.name)
+
+	case flagUnknownShorthandFlagMessage:
+		c := rune(e.name[0])
+		return fmt.Sprintf("unknown shorthand flag: %q in -%s", c, e.specifiedShorthands)
+	}
+
+	panic(fmt.Errorf("unknown flagNotExistErrorMessageType: %v", e.messageType))
+}
+
+// GetSpecifiedName returns the name of the flag (without dashes) as it
+// appeared in the parsed arguments.
+func (e *NotExistError) GetSpecifiedName() string {
+	return e.name
+}
+
+// GetSpecifiedShortnames returns the group of shorthand arguments
+// (without dashes) that the flag appeared within. If the flag was not in a
+// shorthand group, this will return an empty string.
+func (e *NotExistError) GetSpecifiedShortnames() string {
+	return e.specifiedShorthands
+}
+
+// ValueRequiredError is the error returned when a flag needs an argument but
+// no argument was provided.
+type ValueRequiredError struct {
+	flag                *Flag
+	specifiedName       string
+	specifiedShorthands string
+}
+
+// Error implements error.
+func (e *ValueRequiredError) Error() string {
+	if len(e.specifiedShorthands) > 0 {
+		c := rune(e.specifiedName[0])
+		return fmt.Sprintf("flag needs an argument: %q in -%s", c, e.specifiedShorthands)
+	}
+
+	return fmt.Sprintf("flag needs an argument: --%s", e.specifiedName)
+}
+
+// GetFlag returns the flag for which the error occurred.
+func (e *ValueRequiredError) GetFlag() *Flag {
+	return e.flag
+}
+
+// GetSpecifiedName returns the name of the flag (without dashes) as it
+// appeared in the parsed arguments.
+func (e *ValueRequiredError) GetSpecifiedName() string {
+	return e.specifiedName
+}
+
+// GetSpecifiedShortnames returns the group of shorthand arguments
+// (without dashes) that the flag appeared within. If the flag was not in a
+// shorthand group, this will return an empty string.
+func (e *ValueRequiredError) GetSpecifiedShortnames() string {
+	return e.specifiedShorthands
+}
+
+// InvalidValueError is the error returned when an invalid value is used
+// for a flag.
+type InvalidValueError struct {
+	flag  *Flag
+	value string
+	cause error
+}
+
+// Error implements error.
+func (e *InvalidValueError) Error() string {
+	flag := e.flag
+	var flagName string
+	if flag.Shorthand != "" && flag.ShorthandDeprecated == "" {
+		flagName = fmt.Sprintf("-%s, --%s", flag.Shorthand, flag.Name)
+	} else {
+		flagName = fmt.Sprintf("--%s", flag.Name)
+	}
+	return fmt.Sprintf("invalid argument %q for %q flag: %v", e.value, flagName, e.cause)
+}
+
+// Unwrap implements errors.Unwrap.
+func (e *InvalidValueError) Unwrap() error {
+	return e.cause
+}
+
+// GetFlag returns the flag for which the error occurred.
+func (e *InvalidValueError) GetFlag() *Flag {
+	return e.flag
+}
+
+// GetValue returns the invalid value that was provided.
+func (e *InvalidValueError) GetValue() string {
+	return e.value
+}
+
+// InvalidSyntaxError is the error returned when a bad flag name is passed on
+// the command line.
+type InvalidSyntaxError struct {
+	specifiedFlag string
+}
+
+// Error implements error.
+func (e *InvalidSyntaxError) Error() string {
+	return fmt.Sprintf("bad flag syntax: %s", e.specifiedFlag)
+}
+
+// GetSpecifiedName returns the exact flag (with dashes) as it
+// appeared in the parsed arguments.
+func (e *InvalidSyntaxError) GetSpecifiedFlag() string {
+	return e.specifiedFlag
+}