Create `component_dir` substitution for local files to be included in… (#6575)

tests/components/font/test.esp32-idf.yaml

@@ -1,19 +1,7 @@
-i2c:
-  - id: i2c_font
-    scl: 16
-    sda: 17
+substitutions:
+  i2c_scl: GPIO16
+  i2c_sda: GPIO17
+  display_reset_pin: GPIO13
 
-display:
-  - platform: ssd1306_i2c
-    id: ssd1306_display
-    model: SSD1306_128X64
-    reset_pin: 13
-    pages:
-      - id: page1
-        lambda: |-
-          it.rectangle(0, 0, it.get_width(), it.get_height());
-
-font:
-  - file: "gfonts://Roboto"
-    id: roboto
-    size: 20
+packages:
+  common: !include common.yaml