Make CTRL signal able to take multiple contexts

[JohnMcPMS]

Related to #1009 , fixes one of the problems but there are many listed.

Change

Update the CTRL signal handler to be able to fan out to multiple contexts, and make all cases of using sub-contexts both connected to the signal handler and better handle cancellation.

Additionally, improve the COM API install method to properly cancel any in progress task rather than just terminating the context.

Validation

Manually ensured that CTRL+C cancels various multi-step commands.

Microsoft Reviewers: Open in CodeFlow

[github-actions]

Misspellings found, please review:

• subcontext

To accept these changes, run the following commands from this repository on this branch

pushd $(git rev-parse --show-toplevel)
perl -e '
my @expect_files=qw('".github/actions/spelling/expect.txt"');
@ARGV=@expect_files;
my @stale=qw('"abifind bcp cdn CLSID combaseapi compschema cppwinrtprocess Debian Globals google IApp idl IFind IGet iinstall INET Langs MIDL oss Packageend pseudocode REINSTALLMODE smartscreen sourc Standalone vamus Wunused Xaml "');
my $re=join "|", @stale;
my $suffix=".".time();
my $previous="";
sub maybe_unlink { unlink($_[0]) if $_[0]; }
while (<>) {
  if ($ARGV ne $old_argv) { maybe_unlink($previous); $previous="$ARGV$suffix"; rename($ARGV, $previous); open(ARGV_OUT, ">$ARGV"); select(ARGV_OUT); $old_argv = $ARGV; }
  next if /^(?:$re)(?:(?:\r|\n)*$| .*)/; print;
}; maybe_unlink($previous);'
perl -e '
my $new_expect_file=".github/actions/spelling/expect.txt";
use File::Path qw(make_path);
make_path ".github/actions/spelling";
open FILE, q{<}, $new_expect_file; chomp(my @words = <FILE>); close FILE;
my @add=qw('"clsid debian globals inet langs midl standalone subcontext "');
my %items; @items{@words} = @words x (1); @items{@add} = @add x (1);
@words = sort {lc($a) cmp lc($b)} keys %items;
open FILE, q{>}, $new_expect_file; for my $word (@words) { print FILE "$word\n" if $word =~ /\w/; };
close FILE;'
popd

[yao-msft]