Feature/adjust colors contrast tool (#4544)

# Description of Changes

- Addition of the "Adjust Colors/Contrast" tool

---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

frontend/public/locales/en-GB/translation.json

@@ -547,7 +547,7 @@
     "adjustContrast": {
       "tags": "contrast,brightness,saturation",
       "title": "Adjust Colours/Contrast",
-      "desc": "Adjust Contrast, Saturation and Brightness of a PDF"
+      "desc": "Adjust Colors/Contrast, Saturation and Brightness of a PDF"
     },
     "crop": {
       "tags": "trim,cut,resize",
@@ -2791,8 +2791,9 @@
     "submit": "Sanitize PDF"
   },
   "adjustContrast": {
-    "title": "Adjust Contrast",
-    "header": "Adjust Contrast",
+    "title": "Adjust Colors/Contrast",
+    "header": "Adjust Colors/Contrast",
+    "basic": "Basic Adjustments",
     "contrast": "Contrast:",
     "brightness": "Brightness:",
     "saturation": "Saturation:",