interface: define TMS sequence command

For support of SWD we need to be able to clock out special bit
sequences over TMS or SWDIO.  Create this as a generic operation,
not yet called by anything, which is split as usual into:

 - upper level abstraction ... here, jtag_add_tms_seq();
 - midlayer implementation logic hooking that to the lowlevel code;
 - lowlevel minidriver operation ... here, interface_add_tms_seq();
 - message type for request queue, here JTAG_TMS.

This is done slightly differently than other operations: there's a flag
saying whether the interface driver supports this request.  (In fact a
flag *word* so upper layers can learn about other capabilities too ...
for example, supporting SWD operations.)

That approach (flag) lets this method *eventually* be used to eliminate
pathmove() and statemove() support from most adapter drivers, by moving
all that logic into the mid-layer and increasing uniformity between the
various drivers.  (Which will in turn reduce subtle bugginess.)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

src/jtag/minidriver.h

@@ -67,6 +67,8 @@ int interface_jtag_add_tlr(void);
 int interface_jtag_add_pathmove(int num_states, const tap_state_t* path);
 int interface_jtag_add_runtest(int num_cycles, tap_state_t endstate);
 
+int interface_add_tms_seq(unsigned num_bits, const uint8_t *bits);
+
 /**
  * This drives the actual srst and trst pins. srst will always be 0
  * if jtag_reset_config & RESET_SRST_PULLS_TRST != 0 and ditto for