feat(dbus): Add support for configuring 'revpi-con-can' feature

Introduce the `configure_con_can` function to manage enabling,
disabling, status checking, and availability of the 'revpi-con-can'
feature. Update the `AVAILABLE_FEATURES` dictionary to integrate
'revpi-con-can' as a configurable feature.

src/revpi_middleware/dbus_middleware1/system_config/revpi_config.py

@@ -19,6 +19,8 @@ log = getLogger(__name__)
 
 ConfigVariable = namedtuple("ConfigVariable", ["name", "value", "line_index"])
 
+CONFIG_TXT_LOCATIONS = ("/boot/firmware/config.txt", "/boot/config.txt")
+
 
 class ComputeModuleTypes(IntEnum):
     UNKNOWN = 0
@@ -76,7 +78,7 @@ class RevPiConfig:
             except ValueError:
                 pass
 
-        # Detect WiFi
+        # Detect WiFi on CM module
         could_have_wifi = self._cm_type in (ComputeModuleTypes.CM4, ComputeModuleTypes.CM5)
         if could_have_wifi:
             lst_grep = grep("DRIVER=brcmfmac", "/sys/class/ieee80211/phy0/device/uevent")
@@ -106,7 +108,7 @@ class ConfigTxt:
 
     def __init__(self):
         self._config_txt_path = ""
-        for path in ("/boot/firmware/config.txt", "/boot/config.txt"):
+        for path in CONFIG_TXT_LOCATIONS:
             if exists(path):
                 self._config_txt_path = path
                 break