ls: implement --tree to show as a tree and --level to limit depth for recursion

[skshetry]

$ dvc ls https://github.com/iterative/dataset-registry -TL2
.
├── README.md
├── blog
│   ├── .gitignore
│   └── cats-dogs
├── dvc-course
│   ├── .gitignore
│   └── hymenoptera_data
├── get-started
│   ├── .gitignore
│   └── data.xml
├── github-issues
│   ├── .gitignore
│   └── dataset.parquet
├── images
│   ├── .gitignore
│   ├── dvc-logo-outlines.png
│   ├── owl_sticker.png
│   └── owl_sticker.svg
├── tutorials
│   ├── nlp
│   └── versioning
├── use-cases
│   ├── .gitignore
│   ├── cats-dogs
│   └── pool_data
└── workshop
    ├── .gitignore
    ├── README.md
    ├── dvc_discord_channel.csv
    └── satellite-data

$ dvc ls https://github.com/iterative/dataset-registry -RL2
README.md
blog/.gitignore
blog/cats-dogs
blog/cats-dogs.dvc
dvc-course/.gitignore
dvc-course/hymenoptera_data
dvc-course/hymenoptera_data.dvc
dvc.yaml
get-started/.gitignore
get-started/data.xml
get-started/data.xml.dvc
github-issues/.gitignore
github-issues/dataset.parquet
github-issues/dataset.parquet.dvc
images/.gitignore
images/dvc-logo-outlines.png
images/dvc-logo-outlines.png.dvc
images/owl_sticker.png
images/owl_sticker.png.dvc
images/owl_sticker.svg
images/owl_sticker.svg.dvc
tutorials/nlp
tutorials/versioning
use-cases/.gitignore
use-cases/cats-dogs
use-cases/cats-dogs.dvc
use-cases/pool_data
use-cases/pool_data.dvc
workshop/.gitignore
workshop/README.md
workshop/dvc_discord_channel.csv
workshop/dvc_discord_channel.csv.dvc
workshop/satellite-data
workshop/satellite-data.dvc

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 97.86325% with 5 lines in your changes missing coverage. Please review.

Project coverage is 90.75%. Comparing base (3651939) to head (5b360c5).

Files with missing lines	Patch %	Lines
dvc/commands/ls/__init__.py	95.71%	1 Missing and 2 partials :warning:
dvc/repo/ls.py	95.91%	1 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #10598 +/- ## ========================================== + Coverage 90.71% 90.75% +0.03% ========================================== Files 504 504 Lines 39593 39784 +191 Branches 3129 3140 +11 ========================================== + Hits 35916 36105 +189 + Misses 3030 3021 -9 - Partials 647 658 +11 ```

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