runtime(sh): refactored sh.vim syntax script

- unified bashStatement, kshStatement and shStatement as much as
  possible
- separated builtin commands from external programs
- cleaned up kornshell flavor logic
- fixed alias syntax highlighting
- added test for bash alias syntax highlighting
- removed daemon keyword

closes: #18355

Signed-off-by: Bjoern Foersterling <bjoern.foersterling@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/syntax/testdir/dumps/sh_bash_alias_00.dump

@@ -0,0 +1,20 @@
+>#+0#0000e05#ffffff0|!|/|u|s|r|/|b|i|n|/|b|a|s|h| +0#0000000&@59
+@75
+|a+0#af5f00255&|l|i|a|s| |l+0#00e0e07&|s|=+0#af5f00255&|'|l+0#e000002&|s| |-@1|c|o|l|o|r|=|a|u|t|o|'+0#af5f00255&| +0#0000000&@48
+|~+0#4040ff13&| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|~| @73
+|i+0#0000000&|s|_|b|a|s|h|:| |1|,| @45|1|,|1| @10|A|l@1|