No HighContrast theme for the tables

[Zhirong2022]

Describe the bug
Install the SAS extension base on the official release. Specify the color theme as 'SAS High Contrast', open a table at Library section. No HighContrast theme for the table.

Steps to reproduce
Steps to reproduce the behavior:

1. Sign in with a valid profile
2. Specify the color theme as 'SAS High Contrast' through Manage->Themes->Color Theme
3. Open a table at Library section

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots

Environment (please complete the following information):
Client OS: [e.g. Windows 11]
Extension version: [e.g. v1.1.0]

[clangsmith]

window.activeColorTheme.kind will return ColorThemeKind.Light, Dark, HighContrast, or HighContrastLight. Can see how we are using it in PR #473 to pick an ODS style that reasonably matches VS Code color theme.