chore: code and documentation cleanups, renames and fixes (#4607)

docs/libs/bmp.rst

@@ -13,7 +13,7 @@ sources. For example:
 
 .. code:: c
 
-   lv_img_set_src(my_img, "S:path/to/picture.bmp");
+   lv_image_set_src(my_img, "S:path/to/picture.bmp");
 
 Note that, a file system driver needs to registered to open images from
 files. Read more about it :ref:`file-system` or just
@@ -23,7 +23,7 @@ Limitations
 -----------
 
 -  Only BMP files are supported and BMP images as C array
-   (:c:struct:`lv_img_dsc_t`) are not. It's because there is no practical
+   (:c:struct:`lv_image_dsc_t`) are not. It's because there is no practical
    differences between how the BMP files and LVGL's image format stores
    the image data.
 -  BMP files can be loaded only from file. If you want to store them in

docs/libs/gif.rst

@@ -8,8 +8,8 @@ https://github.com/lecram/gifdec
 When enabled in ``lv_conf.h`` with :c:macro:`LV_USE_GIF`
 :c:expr:`lv_gif_create(parent)` can be used to create a gif widget.
 
-:c:expr:`lv_gif_set_src(obj, src)` works very similarly to :c:func:`lv_img_set_src`.
-As source, it also accepts images as variables (:c:struct:`lv_img_dsc_t`) or
+:c:expr:`lv_gif_set_src(obj, src)` works very similarly to :c:func:`lv_image_set_src`.
+As source, it also accepts images as variables (:c:struct:`lv_image_dsc_t`) or
 files.
 
 Convert GIF files to C array

docs/libs/tjpgd.rst

@@ -30,13 +30,13 @@ Overview
 Usage
 -----
 
-If enabled in ``lv_conf.h`` by :c:macro:`LV_USE_SJPG` LVGL will register a new
-image decoder automatically so JPG and SJPG files can be directly used
+If enabled in ``lv_conf.h`` by :c:macro:`LV_USE_TJPGD` LVGL will register a new
+image decoder automatically so JPG and SJPG files can be used directly
 as image sources. For example:
 
 .. code:: c
 
-   lv_img_set_src(my_img, "S:path/to/picture.jpg");
+   lv_image_set_src(my_img, "S:path/to/picture.jpg");
 
 Note that, a file system driver needs to registered to open images from
 files. Read more about it :ref:`file-system` or just