modem/modem_log_constants: create common folder

A lot of different modem related processes require reading / writing to
the same android system properties. This CL solifies them all into
one place to avoid duplication.

Test: build
Bug: 302435001
Change-Id: I113f43bb68833224f45ad91668cd327587e1649b

modem/modem_log_constants/include/modem_log_constants.h

@@ -0,0 +1,31 @@
+#pragma once
+
+#include <string_view>
+
+namespace pixel_modem::logging {
+
+// Modem related Android System Properties
+
+// Controls triggering `modem_logging_start` and `modem_logging_stop`.
+inline constexpr std::string_view kModemLoggingEnabledProperty =
+    "vendor.sys.modem.logging.enable";
+// Signals the current modem logging state. This will be set to
+// `vendor.sys.modem.logging.enable` when `modem_log_start` or `modem_log_stop`
+// terminates.
+inline constexpr std::string_view kModemLoggingStatusProperty =
+    "vendor.sys.modem.logging.status";
+// Int which specifies how many files to include in the bugreport.
+inline constexpr std::string_view kModemLoggingNumberBugreportProperty =
+    "persist.vendor.sys.modem.logging.br_num";
+// Signals the current location that is being logged to. This can be used to
+// determine the logging type.
+inline constexpr std::string_view kModemLoggingPathProperty =
+    "vendor.sys.modem.logging.log_path";
+
+// Bugreport constants
+inline constexpr int kDefaultBugreportNumberFiles = 100;
+inline constexpr std::string_view kModemAlwaysOnLogDirectory =
+    "/data/vendor/radio/logs/always-on";
+inline constexpr std::string_view kModemLogPrefix = "sbuff_";
+
+}  // namespace pixel_modem::logging