script: shorten jtag_* command names

Drop the get_/set_/_pin/_list noise from the JTAG commands (e.g.
jtag_get_probes_list -> jtag_probes, jtag_set_spi_cs_pin -> jtag_spi_cs,
jtag_spi_rd_wr -> jtag_spi_xfer). jtag_open_probe -> jtag_open (not
jtag_probe, which would clash with jtag_probes under tab-completion).

Hard rename, no aliases. Updates the state-dump emitter, help text,
example script and docs accordingly.

modules/drivers/digilent_jtag/digilent_jtag_drv.c

@@ -198,7 +198,7 @@ static int drv_Digilent_Detect(jtag_core *jc)
     }
 
     /* Release the enumeration table — required before EnumDevices can be
-     * called again (e.g. a second jtag_get_probes_list / open by index). */
+     * called again (e.g. a second jtag_probes / open by index). */
     g_dj.FreeDvcEnum();
 
     g_dj_num_probes = cdvc;
@@ -214,8 +214,8 @@ static int drv_Digilent_Init(jtag_core *jc, int sub_drv, char *params)
 
     (void)params;
 
-    /* Lazy enumeration: jtag_open_probe can be called without going
-     * through jtag_get_probes_list first, so make sure Detect ran. */
+    /* Lazy enumeration: jtag_open can be called without going
+     * through jtag_probes first, so make sure Detect ran. */
     if (g_dj_num_probes == 0) {
         drv_Digilent_Detect(jc);
     }