target: add Espressif ESP32-S2 basic support

ESP32-S2 is a single core Xtensa chip.
Not full featured yet. Some of the missing functionality:
-Semihosting
-Flash breakpoints
-Flash loader
-Apptrace
-FreeRTOS

Signed-off-by: Erhan Kurubas <erhan.kurubas@espressif.com>
Change-Id: I2fb32978e801af5aa21616c581691406ad7cd6bb
Reviewed-on: https://review.openocd.org/c/openocd/+/6940
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-by: Ian Thompson <ianst@cadence.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins

tcl/target/esp32s2.cfg

@@ -0,0 +1,30 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# The ESP32-S2 only supports JTAG.
+transport select jtag
+
+if { [info exists CHIPNAME] } {
+	set _CHIPNAME $CHIPNAME
+} else {
+	set _CHIPNAME esp32s2
+}
+
+if { [info exists CPUTAPID] } {
+	set _CPUTAPID $CPUTAPID
+} else {
+	set _CPUTAPID 0x120034e5
+}
+
+set _TARGETNAME $_CHIPNAME
+set _CPUNAME cpu
+set _TAPNAME $_CHIPNAME.$_CPUNAME
+
+jtag newtap $_CHIPNAME $_CPUNAME -irlen 5 -expected-id $_CPUTAPID
+
+target create $_TARGETNAME esp32s2 -endian little -chain-position $_TAPNAME
+
+xtensa maskisr on
+
+$_TARGETNAME configure -event reset-assert-post { soft_reset_halt }
+
+gdb_breakpoint_override hard