Display Currently Active Dropdown Option as Selected

[muya]

For dropdown settings, show the currently active (user-chosen) one as the selected one on the UI.

Fixes #216

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Issue Description

When dropdown options load in settings, the user-selected options are not shown as the currently selected item.

Steps to Reproduce

We can use the "Capitalize Headings > Style" option to demonstrate.

1. Open Obsidian Linter settings, and scroll down to the "Capitalize Headings" section
2. For the "Style" dropdown, choose a setting that's different from what's currently enabled. For example, if "Title Case" is currently your preferred setting, choose "All Caps".
3. Close the settings page. (Optional: test that the linter is now changing headings to "ALL CAPS").
4. Re-open the settings page, and scroll down to "Capitalize Headings"

Expected: that the newly selected option "ALL CAPS" is chosen as the Style (i.e. with a checkmark), and is currently shown

Actual: "Title Case" is still chosen as the Style, and it has the checkmark.

(see full details in #216)

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Testing

• Manual testing was done to verify this change
• Any guidance on how / where we can add unit tests for this would be appreciated

Before Fix

The value shown in the drop-down always defaults to "Title Case", despite the currently selected user setting

obsidian-linter-dropdown-settings-display-before-fix.mp4

After Fix

The currently selected user setting is now displayed as the active option in the dropdown

obsidian-linter-dropdown-settings-display-after-fix.mp4

[platers]

Thanks for the detailed documentation and fix!