tree-wide: clean up --help texts a bit

This cleans up and unifies the outut of --help texts a bit:

1. Highlight the human friendly description string, not the command
   line via ANSI sequences. Previously both this description string and
   the brief command line summary was marked with the same ANSI
   highlight sequence, but given we auto-page to less and less does not
   honour multi-line highlights only the command line summary was
   affectively highlighted. Rationale: for highlighting the description
   instead of the command line: the command line summary is relatively
   boring, and mostly the same for out tools, the description on the
   other hand is pregnant, important and captions the whole thing and
   hence deserves highlighting.

2. Always suffix "Options" with ":" in the help text

3. Rename "Flags" →  "Options" in one case

4. Move commands to the top in a few cases

5. add coloring to many more help pages

6. Unify on COMMAND instead of {COMMAND} in the command line summary.
   Some tools did it one way, others the other way. I am not sure what
   precisely {} is supposed to mean, that uppercasing doesn't, hence
   let's simplify and stick to the {}-less syntax

And minor other tweaks.

src/machine/machinectl.c

@@ -2690,9 +2690,9 @@ static int help(int argc, char *argv[], void *userdata) {
         if (r < 0)
                 return log_oom();
 
-        printf("%s%s [OPTIONS...] {COMMAND} ...\n\n"
-               "Send control commands to or query the virtual machine and container\n"
-               "registration manager.%s\n"
+        printf("%s [OPTIONS...] COMMAND ...\n\n"
+               "%sSend control commands to or query the virtual machine and container%s\n"
+               "%sregistration manager.%s\n"
                "\nMachine Commands:\n"
                "  list                        List running VMs and containers\n"
                "  status NAME...              Show VM/container details\n"
@@ -2732,7 +2732,7 @@ static int help(int argc, char *argv[], void *userdata) {
                "  export-raw NAME [FILE]      Export a RAW container or VM image locally\n"
                "  list-transfers              Show list of downloads in progress\n"
                "  cancel-transfer             Cancel a download\n"
-               "\nOptions\n"
+               "\nOptions:\n"
                "  -h --help                   Show this help\n"
                "     --version                Show package version\n"
                "     --no-pager               Do not pipe output into a pager\n"
@@ -2762,8 +2762,10 @@ static int help(int argc, char *argv[], void *userdata) {
                "                              checksum, signature)\n"
                "     --force                  Download image even if already exists\n"
                "\nSee the %s for details.\n"
-               , ansi_highlight()
                , program_invocation_short_name
+               , ansi_highlight()
+               , ansi_normal()
+               , ansi_highlight()
                , ansi_normal()
                , link
         );