fix: Handle multiline sql without spaces

[nossrannug]

When replacing multiline comment, it is now done with a space instead of
nothing since this would be valid sql:

SELECT pid FROM/*comment*/pg_stat_activity;

But replacing the comment with "" would make it incorrect.

Also join the lines in query on getContent with a space to remove the
need for spaces in the sql. Previously this sql:

SELECT some_column
FROM some_table;

would result in this error: [error] column "some_columnfrom" does not exist
This PR fixes that.

[joereynolds]

Hey @nossrannug thanks for this, I'll try and take a proper look at it in the week, looks good though!

[joereynolds]

Hey again @nossrannug,

I've just given this a go and there's a few test failures when running npm test.

Let me know if you need any help with them.
I've added github actions to the repo so that tests run on pull requests now too

[joereynolds]

Also, would this solve this longstanding issue:

#55

?

[nossrannug]

Thanks, @joereynolds.
I'll take a look at the tests :) and yes, it looks like this will solve #55