The buttons are not highlight in "Deployment Pane"

**OS:** Win11
**Build Version:** 0.26.170

**Repro Steps:**
1. Select "Dark High Contrast" theme for VS Code.
2. Create a [main.zip](https://github.com/Azure/bicep/files/14919138/main.zip) file with the following and open it in VSCODE.
3. Right click the file -> Click "Show Deployment Pane to the Side".
4. Check whether the buttons are highlight in "Deployment Pane" or not.

**Expect:**
The buttons are highlight in "Deployment Pane", such as they are in "Light High Contrast" theme.

**Actual:**
The buttons are not highlight in "Deployment Pane".

**More Info:**
1. This issue also reproduces in "High Contrast" themes setting by windows.
2. This issue does not reproduce in "Light High Contrast" theme.

Reproduce the issue in the Bicep VS Code experience using the provided main.zip and the listed Dark High Contrast, High Contrast, and Light High Contrast themes. Inspect the Deployment Pane styling and compare button highlighting across themes; done means the buttons are visibly highlighted in the dark and Windows High Contrast themes as they are in Light High Contrast.

Written by the indexing model from the issue text.