Prefer explicit construction to coercion in record initialization

While we support initializing records via coercion from an expression
list, e.g.,

    local x: X = [$x1=1, $x2=2];

this can sometimes obscure the code to readers, e.g., when assigning to
value declared and typed elsewhere. The language runtime has a similar
overhead since instead of just constructing a known type it needs to
check at runtime that the coercion from the expression list is valid;
this can be slower than just writing the readible code in the first
place, see #4559.

With this patch we use explicit construction, e.g.,

    local x = X($x1=1, $x2=2);

scripts/base/frameworks/logging/writers/ascii.zeek

@@ -7,9 +7,9 @@
 ##! names is printed out as meta information, with no "# fields" prepended; no
 ##! other meta data gets included in that mode.  Example filter using this::
 ##!
-##!    local f: Log::Filter = [$name = "my-filter",
-##!                            $writer = Log::WRITER_ASCII,
-##!                            $config = table(["tsv"] = "T")];
+##!    local f = Log::Filter($name = "my-filter",
+##!                          $writer = Log::WRITER_ASCII,
+##!                          $config = table(["tsv"] = "T"));
 ##!
 
 module LogAscii;