[Feature] Support Segmenter (#955)

* segmenter: add model

* update

* readme: update

* config: update

* segmenter: update readme

* segmenter: update

* segmenter: update

* segmenter: update

* configs: set checkpoint path to pretrain folder

* segmenter: modify vit-s/lin, remove data config

* rreadme: update

* configs: transfer from _base_ to segmenter

* configs: add 8x1 suffix

* configs: remove redundant lines

* configs: cleanup

* first attempt

* swipe CI error

* Update mmseg/models/decode_heads/__init__.py

Co-authored-by: Junjun2016 <hejunjun@sjtu.edu.cn>

* segmenter_linear: use fcn backbone

* segmenter_mask: update

* models: add segmenter vit

* decoders: yapf+remove unused imports

* apply precommit

* segmenter/linear_head: fix

* segmenter/linear_header: fix

* segmenter: fix mask transformer

* fix error

* segmenter/mask_head: use trunc_normal init

* refactor segmenter head

* Fetch upstream (#1)

* [Feature] Change options to cfg-option (#1129)

* [Feature] Change option to cfg-option

* add expire date and fix the docs

* modify docstring

* [Fix] Add <!-- [ABSTRACT] --> in metafile #1127

* [Fix] Fix correct num_classes of HRNet in LoveDA dataset #1136

* Bump to v0.20.1 (#1138)

* bump version 0.20.1

* bump version 0.20.1

* [Fix] revise --option to --options #1140

Co-authored-by: Rockey <41846794+RockeyCoss@users.noreply.github.com>
Co-authored-by: MengzhangLI <mcmong@pku.edu.cn>

* decode_head: switch from linear to fcn

* fix init list formatting

* configs: remove variants, keep only vit-s on ade

* align inference metric of vit-s-mask

* configs: add vit t/b/l

* Update mmseg/models/decode_heads/segmenter_mask_head.py

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

* Update mmseg/models/decode_heads/segmenter_mask_head.py

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

* Update mmseg/models/decode_heads/segmenter_mask_head.py

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

* Update mmseg/models/decode_heads/segmenter_mask_head.py

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

* Update mmseg/models/decode_heads/segmenter_mask_head.py

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

* model_converters: use torch instead of einops

* setup: remove einops

* segmenter_mask: fix missing imports

* add necessary imported init funtion

* segmenter/seg-l: set resolution to 640

* segmenter/seg-l: fix test size

* fix vitjax2mmseg

* add README and unittest

* fix unittest

* add docstring

* refactor config and add pretrained link

* fix typo

* add paper name in readme

* change segmenter config names

* fix typo in readme

* fix typos in readme

* fix segmenter typo

* fix segmenter typo

* delete redundant comma in config files

* delete redundant comma in config files

* fix convert script

* update lateset master version

Co-authored-by: MengzhangLI <mcmong@pku.edu.cn>
Co-authored-by: Junjun2016 <hejunjun@sjtu.edu.cn>
Co-authored-by: Rockey <41846794+RockeyCoss@users.noreply.github.com>
Co-authored-by: Miao Zheng <76149310+MeowZheng@users.noreply.github.com>