## [Datasets] Add Mapillary Vistas Datasets to MMSeg Core Package .
## Motivation
Add Mapillary Vistas Datasets to core package.
Old PR #2484 

## Modification
- Add Mapillary Vistas Datasets to core package.
- Delete `tools/datasets_convert/mapillary.py` , dataset does't need
converting.
- Add `schedule_240k.py`  config.
- Add configs files.  
  ```none
  deeplabv3plus_r101-d8_4xb2-240k_mapillay_v1-512x1024.py
  deeplabv3plus_r101-d8_4xb2-240k_mapillay_v2-512x1024.py
  maskformer_swin-s_4xb2-240k_mapillary_v1-512x1024.py
  maskformer_swin-s_4xb2-240k_mapillary_v2-512x1024.py
  maskformer_r101-d8_4xb2-240k_mapillary_v1-512x1024.py
  maskformer_r101-d8_4xb2-240k_mapillary_v2-512x1024.py
  pspnet_r101-d8_4xb2-240k_mapillay_v1-512x1024.py
  pspnet_r101-d8_4xb2-240k_mapillay_v2-512x1024.py
  ```
- Synchronized changes to `projects/mapillary_datasets`

---------

Co-authored-by: Miao Zheng <76149310+MeowZheng@users.noreply.github.com>
Co-authored-by: xiexinch <xiexinch@outlook.com>