cmd: improve `kes migrate` command

[aead]

This commit improves the kes migrate command.

It now uses the lipgloss text UI framework instead of handwritten code.

As side-effect, this commit removes the direct github.com/fatih/color dependency.

Migrating keys from one KMS instance to another one may now look as following:

Starting key migration...

Source:   Filesystem /tmp/1
Target:   Filesystem /tmp/2

Warning: Existing keys will be overwritten.
Migrated 3 keys in 3s DONE

Testing this PR

1. Setup two KES instance (source and target). Therefore create a new TLS private/public key pair:

   kes identity new --ip 127.0.0.1 --dns localhost localhost

2. Create the source KES instance with the following config:

   admin: 
    identity: 3ecfcdf38fcbe141ae26a1030f81e96b753365a46760ae6b578698a97c59fd22
   
   tls:
    key: private.key
    cert: public.crt
   
   keys:
   - name: my-key-1
   - name: my-key-2
   - name: my-key-3
   
   keystore:
    fs:
      path: /tmp/1

   kes server --config source.yml --auth off

3. Create the target KES instance with the following config:

   admin: 
    identity: 3ecfcdf38fcbe141ae26a1030f81e96b753365a46760ae6b578698a97c59fd22
   
   tls:
    key: private.key
    cert: public.crt
   
   keystore:
    fs:
      path: /tmp/2

   kes server --config target.yml --auth off

4. Migrate the keys from the source to the target:

   kes migrate --from source.yml --to target.yml

[shtripat]

Kindly resolve the conflict

[harshavardhana]

PTAL @aead conflicts

[harshavardhana]

PTAL @aead conflicts

@aead ^^ is this PR still needed?

[allanrogerr]

@aead PTAL

[harshavardhana]

I am closing this PR as stale and outdated.