Add validation constraints to user.flood

Problem/Motivation

The User module's flood have 4 property paths that are not yet validatable:

vendor/bin/drush config:inspect --filter-keys=user.flood  --detail --list-constraints  --fields=key,validatability,constraints
➜  🤖 Analyzing…

 --------------------- ------------- ------------------------------------- 
  Key                   Validatable   Validation constraints               
 --------------------- ------------- ------------------------------------- 
  user.flood            50%           ValidKeys:'<infer>'                 
   user.flood:          Validatable   ValidKeys: '<infer>'                 
   user.flood:_core     Validatable   ValidKeys:                           
                                        - default_config_hash              
   user.flood:_core.d   Validatable   NotNull: {  }                        
  efault_config_hash                  Regex: '/^[a-zA-Z0-9\-_]+$/'         
                                      Length: 43                           
                                      ↣ PrimitiveType: {  }                
   user.flood:ip_limi   NOT           ⚠️  @todo Add validation constraints  
  t                                   here                                 
   user.flood:ip_wind   NOT           ⚠️  @todo Add validation constraints  
  ow                                  here                                 
   user.flood:uid_onl   Validatable   ↣ PrimitiveType: {  }                
  y                                                                        
   user.flood:user_li   NOT           ⚠️  @todo Add validation constraints  
  mit                                 here                                 
   user.flood:user_wi   NOT           ⚠️  @todo Add validation constraints  
  ndow                                here                                 
 --------------------- ------------- ------------------------------------- 

Steps to reproduce

1. Get a local git clone of Drupal core 11.x.
2. composer require drupal/config_inspector— or manually install https://www.drupal.org/project/config_inspector/releases/2.1.5 or newer (which supports Drupal 11!)
3. composer require drush/drush
4. vendor/bin/drush config:inspect --filter-keys=user.flood --detail --list-constraints

Proposed resolution

1. Add validation constraints.
2. Mark FullyValidatable.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet