Update eslint to v9

[cloke]

While working towards a v2 add-on it became clear very quickly that step one would be to update many of the various dependencies.

This pull request includes significant updates to the codebase, primarily focusing on removing ESLint configurations and updating dependencies. Additionally, minor code formatting changes were made across various files.

Removal of ESLint configurations:

• .eslintignore: Removed the entire file, which previously specified files and directories to be ignored by ESLint.
• .eslintrc.js: Removed the entire ESLint configuration file, which included parser settings, plugins, environments, and rules.
• node-test/.eslintrc.js: Removed the ESLint configuration specific to node tests.

Dependency updates:

• package.json: Updated several dependencies, including eslint, eslint-config-prettier, eslint-plugin-ember, eslint-plugin-prettier, and prettier. Removed babel-eslint and updated other dependencies to their latest versions. [1] [2]

Code formatting changes:

• addon/utils/get-messages.js: Added trailing commas to function parameters. [1] [2]
• addon/utils/handle-multiple-validations.js: Added trailing commas to function parameters and array elements. [1] [2]
• addon/utils/to-date.js: Removed unnecessary ESLint comments.
• addon/utils/validation-errors.js: Added trailing commas to function parameters and object properties.

Test file formatting changes:

• Various test files: Added trailing commas to function parameters, array elements, and object properties to improve code consistency. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16]