logging: Add separate logger for health monitoring

Before this patch all logs from the health monitoring part used 'main'
logger. This patch creates a new logger ('health') and health monitoring
parts of code use this logger.

Change-Id: I7bfa1b2197a06d3c9edb29e7ec45ba77c54b11ad
diff --git a/src/health/outputs/LedSysfsDriver.cpp b/src/health/outputs/LedSysfsDriver.cpp
index c3b0f0f..73e460d 100644
--- a/src/health/outputs/LedSysfsDriver.cpp
+++ b/src/health/outputs/LedSysfsDriver.cpp
@@ -12,7 +12,7 @@
 namespace velia::health {
 
 LedSysfsDriver::LedSysfsDriver(const std::filesystem::path& directory)
-    : m_log(spdlog::get("main"))
+    : m_log(spdlog::get("health"))
     , m_brightnessFile(directory / "brightness")
 {
     // check that brightness file exists