workspace/didChangeWatchedFiles never triggered under /tmp through registered successfully

[oxalica]

Result from CocInfo

vim version: VIM - Vi IMproved 9.0 9001441
node version: v18.15.0
coc.nvim version: 0.0.82-b7375d5f 2023-01-30 05:09:03 +0800
coc.nvim directory: /nix/store/kppjv8524nb63jc8zsh5g5ycss6snf0k-vimplugin-coc.nvim-2023-01-29
term: tmux
platform: linux

Describe the bug

In the code:

coc.nvim/src/core/watchman.ts

Line 180 in 3014125

if (root.startsWith('/tmp/') || root.startsWith('/private/tmp/')) return false

Any directory (recursively) under /tmp is ignored from watching. I can understand watching the full /tmp is problematic, but it's reasonable to create a /tmp/some-test-project/ and use coc.nvim in it for testing. We should allow this case.

EDIT: vscode watches files successfully and can correctly emit change events for /tmp/some-dir/some-file.

Reproduce the bug

Language server request:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "client/registerCapability",
  "params": {
    "registrations": [
      {
        "id": "workspace/didChangeWatchedFiles",
        "method": "workspace/didChangeWatchedFiles",
        "registerOptions": {
          "watchers": [
            {
              "globPattern": {
                "baseUri": "file:///tmp/flake",
                "pattern": "flake.lock"
              }
            },
            {
              "globPattern": {
                "baseUri": "file:///tmp/flake",
                "pattern": "flake.nix"
              }
            }
          ]
        }
      }
    ]
  }
}

Success response from coc.nvim:

{"jsonrpc":"2.0","id":1,"result":null}

But it never generates any notifications since the watched files are under /tmp.

Expected behavior

1. /tmp can be an invalid watching directory, but /tmp/some-dir should not.
2. If coc.nvim cannot fulfill the watching request (eg. invalid watching directory, or watchman is not installed), it should return an error response for easier debugging. It also allows the server to fallback to server-side watching mechanism.

[fannheyward]

Maybe we can replace the startWith checking with must equal, to stop watching /tmp but /tmp/some-dir not.