feat: Implement SSH Agent Connector and gRPC server

- Added `AgentConnectorTrait` and `AgentConnector` for managing agent connections.
- Introduced `SshAgentConnector` to handle SSH-related functionalities and start a gRPC server.
- Created database entities for `agents`, `certificates`, `organizations`, `public_key_revocations`, `setup_tokens`, `upstreams`, `users`, `virtual_hosts`, and `workspaces` using SeaORM.
- Developed `CertificateService` for managing certificate generation and retrieval.
- Implemented the main server logic to initialize the database connection and start the agent server.
- Configured development settings in `development.toml` for server and database connections.

apps/nxmesh-master/src/db/entities/agents.rs

@@ -0,0 +1,27 @@
+//! `SeaORM` Entity, @generated by sea-orm-codegen 2.0
+
+use sea_orm::entity::prelude::*;
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone, Debug, PartialEq, Eq, DeriveEntityModel, Serialize, Deserialize)]
+#[sea_orm(table_name = "agents")]
+pub struct Model {
+    #[sea_orm(primary_key, auto_increment = false)]
+    pub id: Uuid,
+    pub name: String,
+    pub ip_address: Option<String>,
+    pub version: Option<String>,
+    pub state: String,
+    pub deployment_mode: Option<String>,
+    pub last_seen_at: Option<DateTimeWithTimeZone>,
+    pub capabilities: Option<Json>,
+    pub public_key_hash: Option<String>,
+    pub labels: Option<Json>,
+    pub created_at: DateTimeWithTimeZone,
+    pub updated_at: DateTimeWithTimeZone,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+pub enum Relation {}
+
+impl ActiveModelBehavior for ActiveModel {}