feat: base layer for unread counts (store, counter and builder) (1/3)[CW-6851] (#14368)

## Description

This is the first PR in a series of PRs for Introducing unread counts in
the sidebar for inboxes and labels.

In this PR:

* Added the unread store, counter and builder modules
* Added redis keys for unread count management
* Added specs for all 3 modules, some specs are for testing enterprise
only feature like specific roles and permissions which are added in the
respective enterprise folder itself.

**Note**
None of this changes affect anything else and nothing is wired to
existing modules.

Issue:
https://linear.app/chatwoot/issue/CW-6851/support-unread-conversation-counts

## Type of change

Please delete options that are not relevant.

- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality not to work as expected)
- [ ] This change requires a documentation update

## How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide
instructions so we can reproduce. Please also list any relevant details
for your test configuration.


## Checklist:

- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [ ] I have commented on my code, particularly in hard-to-understand
areas
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged and published in downstream
modules

---------

Co-authored-by: Sojan Jose <sojan@pepalo.com>

lib/redis/alfred.rb

@@ -40,6 +40,11 @@ module Redis::Alfred
       $alfred.with { |conn| conn.expire(key, seconds) }
     end
 
+    # get expiry of a key in seconds
+    def ttl(key)
+      $alfred.with { |conn| conn.ttl(key) }
+    end
+
     # scan keys matching a pattern
     def scan_each(match: nil, count: 100, &)
       $alfred.with do |conn|
@@ -80,6 +85,10 @@ module Redis::Alfred
       $alfred.with { |conn| conn.lrem(key, count, value) }
     end
 
+    def pipelined(&)
+      $alfred.with { |conn| conn.pipelined(&) }
+    end
+
     # hash operations
 
     # add a key value to redis hash

lib/redis/lock_manager.rb

@@ -49,6 +49,18 @@ class Redis::LockManager
     true
   end
 
+  def with_lock(key, timeout = LOCK_TIMEOUT)
+    return false unless lock(key, timeout)
+
+    begin
+      yield
+    ensure
+      unlock(key)
+    end
+
+    true
+  end
+
   # Checks if the given key is currently locked.
   #
   # === Parameters

lib/redis/redis_keys.rb

@@ -9,6 +9,28 @@ module Redis::RedisKeys
   # Whether a conversation is muted ?
   CONVERSATION_MUTE_KEY = 'CONVERSATION::%<id>d::MUTED'.freeze
   CONVERSATION_DRAFT_MESSAGE = 'CONVERSATION::%<id>d::DRAFT_MESSAGE'.freeze
+  UNREAD_CONVERSATIONS_ACCOUNT_PREFIX = 'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d'.freeze
+  UNREAD_CONVERSATIONS_BASE_READY = 'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d::READY::BASE'.freeze
+  UNREAD_CONVERSATIONS_ASSIGNMENT_READY = 'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d::READY::ASSIGNMENT'.freeze
+  UNREAD_CONVERSATIONS_BASE_BUILD_LOCK = 'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d::BUILD_LOCK::BASE'.freeze
+  UNREAD_CONVERSATIONS_ASSIGNMENT_BUILD_LOCK = 'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d::BUILD_LOCK::ASSIGNMENT'.freeze
+  UNREAD_CONVERSATIONS_INBOX = 'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d::INBOX::%<inbox_id>d'.freeze
+  UNREAD_CONVERSATIONS_LABEL_INBOX =
+    'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d::LABEL::%<label_id>d::INBOX::%<inbox_id>d'.freeze
+  UNREAD_CONVERSATIONS_TEAM_INBOX =
+    'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d::TEAM::%<team_id>d::INBOX::%<inbox_id>d'.freeze
+  UNREAD_CONVERSATIONS_INBOX_UNASSIGNED =
+    'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d::INBOX::%<inbox_id>d::UNASSIGNED'.freeze
+  UNREAD_CONVERSATIONS_INBOX_ASSIGNEE =
+    'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d::INBOX::%<inbox_id>d::ASSIGNEE::%<user_id>d'.freeze
+  UNREAD_CONVERSATIONS_LABEL_INBOX_UNASSIGNED =
+    'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d::LABEL::%<label_id>d::INBOX::%<inbox_id>d::UNASSIGNED'.freeze
+  UNREAD_CONVERSATIONS_LABEL_INBOX_ASSIGNEE =
+    'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d::LABEL::%<label_id>d::INBOX::%<inbox_id>d::ASSIGNEE::%<user_id>d'.freeze
+  UNREAD_CONVERSATIONS_TEAM_INBOX_UNASSIGNED =
+    'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d::TEAM::%<team_id>d::INBOX::%<inbox_id>d::UNASSIGNED'.freeze
+  UNREAD_CONVERSATIONS_TEAM_INBOX_ASSIGNEE =
+    'UNREAD_CONVERSATIONS::V1::ACCOUNT::%<account_id>d::TEAM::%<team_id>d::INBOX::%<inbox_id>d::ASSIGNEE::%<user_id>d'.freeze
 
   ## User Keys
   # SSO Auth Tokens