feat: add uc CLI argument completion for machines, services, volumes (#309)

* Allow for argument completion

This shows for a single command on how to complete service names in the
cluster: `uc inspect <TAB>` will complete using ListServices

See: #307

Signed-off-by: Miek Gieben <miek@miek.nl>

* All cluster interactions can be completed

Signed-off-by: Miek Gieben <miek@miek.nl>

* Machines -m flag completion

Signed-off-by: Miek Gieben <miek@miek.nl>

* Add completion for "ctx use"

Signed-off-by: Miek Gieben <miek@miek.nl>

* Complete from compose file too

Signed-off-by: Miek Gieben <miek@miek.nl>

* Allow for argument completion

This shows for a single command on how to complete service names in the
cluster: `uc inspect <TAB>` will complete using ListServices

See: #307

Signed-off-by: Miek Gieben <miek@miek.nl>

* All cluster interactions can be completed

Signed-off-by: Miek Gieben <miek@miek.nl>

* Machines -m flag completion

Signed-off-by: Miek Gieben <miek@miek.nl>

* Add completion for "ctx use"

Signed-off-by: Miek Gieben <miek@miek.nl>

* Complete from compose file too

Signed-off-by: Miek Gieben <miek@miek.nl>

* Move to better place

Signed-off-by: Miek Gieben <miek@miek.nl>

* Adjust imports

Signed-off-by: Miek Gieben <miek@miek.nl>

* prefix match for context too

Signed-off-by: Miek Gieben <miek@miek.nl>

---------

Signed-off-by: Miek Gieben <miek@miek.nl>

cmd/uncloud/volume/ls.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/psviderski/uncloud/internal/cli"
+	"github.com/psviderski/uncloud/internal/cli/completion"
 	"github.com/psviderski/uncloud/internal/cli/tui"
 	"github.com/psviderski/uncloud/pkg/api"
 	"github.com/spf13/cobra"
@@ -36,6 +37,8 @@ func NewListCommand() *cobra.Command {
 	cmd.Flags().BoolVarP(&opts.quiet, "quiet", "q", false,
 		"Only display volume names.")
 
+	completion.MachinesFlag(cmd)
+
 	return cmd
 }