test: Move str_ut test into lib

This test doesn't belong at the top level. Move it into the lib/
directory, to match (most of) its implementation. Rename it to drop the
unnecessary _ut suffix.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Tom Rini <trini@konsulko.com> # rpi_3, rpi_4, rpi_arm64, am64x_evm_a53, am64-sk

test/Makefile

@@ -14,7 +14,6 @@ endif
 ifneq ($(CONFIG_HUSH_PARSER),)
 obj-$(CONFIG_$(XPL_)CMDLINE) += hush/
 endif
-obj-$(CONFIG_$(XPL_)CMDLINE) += str_ut.o
 obj-$(CONFIG_UT_TIME) += time_ut.o
 obj-y += ut.o
 

test/lib/Makefile

@@ -17,6 +17,7 @@ obj-y += lmb.o
 obj-y += longjmp.o
 obj-$(CONFIG_CONSOLE_RECORD) += test_print.o
 obj-$(CONFIG_SSCANF) += sscanf.o
+obj-$(CONFIG_$(XPL_)CMDLINE) += str.o
 obj-y += string.o
 obj-y += strlcat.o
 obj-$(CONFIG_ERRNO_STR) += test_errno_str.o