feat: initial DB Lab

Description

Initial code for Database Lab. Provision part was mostly migrated from postgres-ai/joe repository, now DB Lab functions separately from the bot. This MR includes: REST API, cloning abstration to support different modules in the future, ZFS module (with meta info gathering), config improvements.

MR introduces number of TODOs which should be closed in upcoming MRs.

Instance statuses:

• OK - instance functions well.
• WARNING - still functional, but have some problems, e.g. disk space shortage, insecure connection (upcoming MRs).

Clone statuses:

• OK - clone is ready to accept postgres connections.
• CREATING - clone is being created.
• DELETING - clone is being deleted.
• FATAL - fatal error happened (details in status message).

Basic models:

Clone
{
  id: "xxx",
  status: {
    code: "OK",
    message: "Database is ready"
  },
  project: "proj1"
  snapshot: "" (optional, ID or timestamp)
  db: {
    username: "postgres"
    password: "" (never set on DB Lab side)
  },
  protected: true
  deleteAt: "" (timestamp),
  name: "",
  username: "",
  createdAt: ""
}

Error
{
  code: "NOT_ENOUGH_DISK_SPACE",
  name: "Not enough disk space",
  hint: "Stop idle clones, change snapshot policy or increase disk size"
}

REST API:

Get DB Lab instance status and list clones
GET /status
Response:
{
  status: {
    code: "OK",
    message: "DB Lab is ready"
  },
  disk: {
    size: 1000.0, (bytes)
    free: 1200.0
  },
  expectedCloningTime: 8.0, (secondss)
  numClones: 10,
  clones: [{
    id: "id"
    status: {
      code: "OK",
      message: "Database is ready"
    },
    ...
  }, ... ],
 snapshots: [{
   id: "xxx",
   timestamp: "123"
 }, ... ]
}

Create a clone
POST /clone/
Request:
{
  project: "proj1",
  snapshot: (optional): "",
  db: {
    username: "xxx",
    password: "xxx"
  }
  username: "xxx",
  name: "xxx"
}
Response:
{
  id: "xxx"
}

Update a clone
PATCH /clone/:id

Reset a clone
POST /clone/:id/reset

Delete a clone
DELETE /clone/:id

Get status of a clone 
GET /clone/:id
Response:
{
  id: "xxx",
  status: {
    code: "OK",
    message: "Database clone is ready"
  },
  cloneSize: 1000.0,
  cloningTime: 5,
  project: "xxx",
  snapshot: "xxx",
  db: {
    username: "xxx",
    host: "xxx",
    port: "xxx",
    connStr: "xxx"
  },
  protected: true,
  deleteAt: "",
  name: "xxx",
  username: "xxx",
  createdAt: "123"
}

Related issue

Closes #1 (closed)

Checklist

• the MR description has been reviewed
• this MR contains text changes and they have been reviewed OR there are no texts changes
• this MR contains GUI/CLI changes and they have been reviewed OR there are no GUI/CLI changes
• this MR contains API changes and they have been reviewed OR there are no API changes