feat: Add --indicate-deeper-levels Flag to eza --tree

Current Issue: Using eza --tree --level=n currently provides no indication of additional nested levels, which can lead to confusion about directory contents when only a limited depth is shown.

Proposed Solution: Introduce a --indicate-deeper-levels flag to mark directories that have further levels beyond the specified depth. A simple indicator (e.g., ...) would clarify that deeper levels exist, improving clarity without altering the specified --level setting.

Example

Original Folder Structure

.
├── a
└── b
   ├── c
   └── d
      └── e

Output of eza --tree --level=1

.
├── a
└── b

Wanted behavior of e.g. eza --tree --level=1 --indicate-deeper-levels

.
├── a
└── b
   └── ...