Backport 'read -a' and 'read -p' from ksh 93v-/2020

This backports two minor additions to the 'read' built-in from ksh
93v-: '-a' is now the same as '-A' and '-u p' is the same as '-p'.
This is for compatibility with some 93v- or ksh2020 scripts.

Note that their change to the '-p' option to support both prompts
and reading from the coprocess was *not* backported because we
found it to be broken and unfixable. Discussoin at:
https://github.com/ksh93/ksh/issues/463

src/cmd/ksh93/bltins/read.c: b_read():
- Backport as described above.
- Rename the misleadingly named 'name' variable to 'prompt'.
  It points to the prompt string, not to a variable name.

src/cmd/ksh93/data/builtins.c: sh_optpwd[]:
- Add -a as an alterative to -A. All that is needed is adding '|a'
  and optget(3) will automatically convert it to 'A'.
- Change -u from a '#' (numeric) to ':' option to support 'p'. Note
  that b_read() now needs a corresponding strtol() to convert file
  descriptor strings to numbers where applicable.
- Tweaks.

src/cmd/ksh93/sh.1:
- Update accordingly.
- Tidy up the unreadable mess that was the 'read' documentation.
  The options are now shown in a list.

src/cmd/ksh93/include/version.h

@@ -21,7 +21,7 @@
 
 #define SH_RELEASE_FORK	"93u+m"		/* only change if you develop a new ksh93 fork */
 #define SH_RELEASE_SVER	"1.0.0-beta.2"	/* semantic version number: https://semver.org */
-#define SH_RELEASE_DATE	"2022-02-15"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2022-02-16"	/* must be in this format for $((.sh.version)) */
 #define SH_RELEASE_CPYR	"(c) 2020-2022 Contributors to ksh " SH_RELEASE_FORK
 
 /* Scripts sometimes field-split ${.sh.version}, so don't change amount of whitespace. */