Feature: Support Adding explicit package entries using option in monas new

[HuM4NoiD]

This pull request adds a flag option to monas new subcommand, which adds an explicit package entry in the root project

$ monas new --help
                                                                                                                                            
 Usage: monas new [OPTIONS] PACKAGE [LOCATION]                                                                                              
                                                                                                                                            
 Create a new <package> under <location>.                                                                                                   
 The package name must be locally unique and available on PyPI.                                                                             
 If location isn't given, it defaults to the first location of `packages` config.                                                           
                                                                                                                                            
╭─ Options ────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╮
│ --explicit-package-entry  -e    If specified, an explicit package entry will be added to the list of packages                            │
│ --help                          Show this message and exit.                                                                              │
╰──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────╯

Example Usage:
The following commands will produce the following root pyproject.toml

$ monas init -n
$ monas new -e service binaries
$ monas new -e utils common
$ monas new -e sample .

[tool.monas]
packages = ["binaries/service", "common/utils", "sample"]
version = "0.0.0"
python-version = "3.11"