bscan: rename from bscan_spi, add TAP primitives for the SVF player

The module outgrew its "SPI bridge" name — it's mostly generic
single-device JTAG TAP primitives now. Rename modules/bscan_spi ->
modules/bscan (dir, files, library target, includes, doc paths);
bscan_* function names and bscan_spi_xfer() kept.

Add the two primitives the SVF player needs beyond shift_dr:
- bscan_shift_ir: general IR scan with TDO capture (bscan_set_ir is
  opcode-only, no readback)
- bscan_tap_reset: force Test-Logic-Reset, land in Run-Test/Idle

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

modules/bscan/CMakeLists.txt

@@ -0,0 +1,7 @@
+set(SOURCE_DIR "${CMAKE_CURRENT_SOURCE_DIR}")
+
+file(GLOB_RECURSE ALL_SOURCES "*.c")
+
+include_directories(${CMAKE_CURRENT_SOURCE_DIR}/..)
+
+add_library(bscan ${ALL_SOURCES})