feat: improved inspection of columns

[sidorares]

ColumnDefinition object for the sake of performance does not store a lot of human readable data: instead of strings it's a buffer and start/end offset, column type is represented as id, flags are compressed into 32 bit int bitfield etc

Here is current result of console.log(columns[0]):

ColumnDefinition {
    _buf: <Buffer 01 00 00 01 08 33 00 00 02 03 64 65 66 05 6d 79 73 71 6c 05 74 61 73 6b 73 05 74 61 73 6b 73 07 74 61 73 6b 5f 69 64 07 74 61 73 6b 5f 69 64 0c 3f 00 ... 431 more bytes>,
    _clientEncoding: 'utf8',
    _catalogLength: 3,
    _catalogStart: 234,
    _schemaLength: 5,
    _schemaStart: 238,
    _tableLength: 5,
    _tableStart: 244,
    _orgTableLength: 5,
    _orgTableStart: 250,
    _orgNameLength: 6,
    _orgNameStart: 263,
    characterSet: 63,
    encoding: 'binary',
    name: 'status',
    columnLength: 4,
    columnType: 1,
    type: 1,
    flags: 4097,
    decimals: 0
  }

there is currently an inspect() method which might have worked ages ago but currently not used.

This pr adds:

• custom inspect method under under util.inspect.custom. 2 modes: depth > 1 returns text as close as possible to part of a "create table" statement, and depth <=1 returns more detailed inspection

• display a field length. Note that this depends on the type and charset, for example VARCHAR(255) has columnLength set to 1020 is current serverEncoding is utf8mb4

• colors and showHidden support maybe later

• unit tests

Examples:

console.log(columns)

[
  `task_id` LONG NOT NULL PRIMARY KEY AUTO_INCREMENT,
  `title` VAR_STRING NOT NULL NO_DEFAULT_VALUE,
  `start_date` DATE,
  `due_date` DATE,
  `status` TINY NOT NULL NO_DEFAULT_VALUE,
  `priority` TINY NOT NULL NO_DEFAULT_VALUE,
  `description` BLOB BLOB,
  `created_at` TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
]

console.log(columns[0]);

{
  catalog: 'def',
  schema: 'mysql',
  name: 'task_id',
  orgName: 'task_id',
  table: 'tasks',
  orgTable: 'tasks',
  characterSet: 63,
  columnLength: 11,
  columnType: 3,
  type: 3,
  flags: [ 'NOT NULL', 'PRIMARY KEY', 'AUTO_INCREMENT' ],
  decimals: 0,
  typeName: 'LONG'
}

[github-actions]

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