Note: The only "bugged" icon is `Search by Import Log Type`. If we can't find a proper light theme version of the icon, let's track whoever introduced the feature. (Current hunch: Asset Importers).

Reproduction steps:
1. Create a new project
2. Change Editor Theme to Light (Unity > Settings… > General)
3. Observe Project window buttons

Actual result: Search by Import Log Type and Number of displayed packages icons are poorly visible
Expected result: Search by Import Log Type, Number of displayed packages and Save search icons are clearly visible and Number of displayed packages and Save search icons are the same color just like in dark theme

Reproducible with: 2021.3.57f1, 2022.3.67f1, 6000.0.60f1, 6000.2.8f1, 6000.3.0b6, 6000.4.0a2

Reproduced on: macOS Sequoia 15.4 (M4)