refactor: rename MyLibrary to FileBrowser (#1260)

## Summary

* Renames MyLibrary component to FileBrowser, as it better reflects what
it is, in my opinion

## Additional Context

* Frees the Library name for possible future library component that can
cache metadata, provide other ways of browsing than filesystem
structure, etc
---

### AI Usage

Did you use AI tools to help write this code? _**< YES >**_

src/activities/ActivityManager.cpp

@@ -5,8 +5,8 @@
 #include "boot_sleep/BootActivity.h"
 #include "boot_sleep/SleepActivity.h"
 #include "browser/OpdsBookBrowserActivity.h"
+#include "home/FileBrowserActivity.h"
 #include "home/HomeActivity.h"
-#include "home/MyLibraryActivity.h"
 #include "home/RecentBooksActivity.h"
 #include "network/CrossPointWebServerActivity.h"
 #include "reader/ReaderActivity.h"
@@ -169,8 +169,8 @@ void ActivityManager::goToFileTransfer() {
 
 void ActivityManager::goToSettings() { replaceActivity(std::make_unique<SettingsActivity>(renderer, mappedInput)); }
 
-void ActivityManager::goToMyLibrary(std::string path) {
-  replaceActivity(std::make_unique<MyLibraryActivity>(renderer, mappedInput, std::move(path)));
+void ActivityManager::goToFileBrowser(std::string path) {
+  replaceActivity(std::make_unique<FileBrowserActivity>(renderer, mappedInput, std::move(path)));
 }
 
 void ActivityManager::goToRecentBooks() {