In the file tree, the icons are not vertically centered, which affects
the overall visual consistency.
Currently, the icons of submodules and symlinks do not adopt the value
of entryIcon, resulting in inconsistent icon display.
before:

after:

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Co-authored-by: silverwind <me@silverwind.io>
1. restore background color
2. fix border radius on top/bottom and on hover
3. parent link is now full-row again, much easier to click
4. parent link now uses directory icon, matching github
5 changed grid layout to remove auto width on file name column which could get too small.
6. mobile layout now shows more of the filename.
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Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
1. use grid instead of table, completely drop "ui table" from that list
2. move some "commit sign" related styles into a new file by the way (no
change) because I need to figure out where `#repo-files-table` is used.
3. move legacy "branch/tag selector" related code into repo-legacy.ts,
now there are 13 `import $` files left.