cmake, refactor: Move handling of Qt TS files into locale directory

This change offers a few advantages, such as:
- a more readable and cleaner `ts_files.cmake` (see the next commit);
- a scoped `ts_files` variable;
- improved code locality;
- no need to adjust the location of the resulting `*.qm` files.

src/qt/CMakeLists.txt

@@ -245,13 +245,7 @@ if(qt_lib_type STREQUAL "STATIC_LIBRARY")
   )
 endif()
 
-file(GLOB ts_files RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} locale/*.ts)
+add_subdirectory(locale)
-set_source_files_properties(${ts_files} PROPERTIES OUTPUT_LOCATION ${CMAKE_CURRENT_BINARY_DIR}/locale)
-if(Qt6_VERSION VERSION_GREATER_EQUAL 6.7)
-  qt6_add_lrelease(TS_FILES ${ts_files} OPTIONS -silent)
-else()
-  qt6_add_lrelease(bitcoinqt TS_FILES ${ts_files} OPTIONS -silent)
-endif()
 
 add_executable(bitcoin-qt
   main.cpp

src/qt/locale/CMakeLists.txt

@@ -0,0 +1,13 @@
+# Copyright (c) 2025-present The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or https://opensource.org/license/mit/.
+
+file(GLOB ts_files RELATIVE ${CMAKE_CURRENT_SOURCE_DIR} "*.ts")
+
+if(Qt6_VERSION VERSION_GREATER_EQUAL 6.7)
+  qt6_add_lrelease(TS_FILES ${ts_files} LRELEASE_TARGET bitcoinqt_lrelease OPTIONS -silent)
+else()
+  qt6_add_lrelease(bitcoinqt TS_FILES ${ts_files} OPTIONS -silent)
+endif()
+
+add_dependencies(bitcoinqt bitcoinqt_lrelease)