feat(console): add command user context support

Current implementation implicitly forces the developer to use global variables
to enter its context during the command invocation, this change enables each
module to register a context for command to find without the need to manage
global variables.

No API breakage.

Fields added:
   esp_console_cmd_t::func_w_context    - (*)(int argc, char **argv, void *context)

Functions added:
   esp_err_t esp_console_cmd_set_context(const char *cmd, void *context)

Usage:

   esp_console_cmd_register(&cmd));
   esp_console_cmd_set_context(cmd.command, (void *)"context"));

Signed-off-by: Alon Bar-Lev <alon.barlev@gmail.com>

docs/en/api-reference/system/console.rst

@@ -147,7 +147,12 @@ For each command, application provides the following information (in the form of
 - Command name (string without spaces)
 - Help text explaining what the command does
 - Optional hint text listing the arguments of the command. If application uses Argtable3 for argument parsing, hint text can be generated automatically by providing a pointer to argtable argument definitions structure instead.
-- The command handler function.
+- Command handler function (without context), or
+- Command handler function (with context). If this function is given, an additional call to :cpp:func:`esp_console_cmd_set_context` must follow *before* the command may be called to initialize the context.
+
+.. note::
+
+  You can either use a command handler function which takes a context or a command handler function which does not take a context, not both. If you use the command handler function which takes a context, you MUST call :cpp:func:`esp_console_cmd_set_context` to initialize its context, otherwise the function may access the uninitialized context.
 
 A few other functions are provided by the command registration module: