Fix string literal length for compressed_data_info

The function `compressed_data_info` returns a record containing `name`
but copies the data from string literal. Since `heap_form_tuple` expects a
`name` value as source as well, it will copy too much data from the
source, leading to ASAN complaining about copying outside the allocated
range of data.

The problem is fixed by using buffers of size `NAMEDATALEN` for each
source string, ensuring that each of the string literals has sufficient
data for being copied as names.

.unreleased/pr_7187

@@ -0,0 +1 @@
+Fixes: #7187 Fix string literal length for compressed_data_info

sql/updates/latest-dev.sql

@@ -1,3 +1,5 @@
 CREATE FUNCTION _timescaledb_functions.compressed_data_info(_timescaledb_internal.compressed_data)
     RETURNS TABLE (algorithm name, has_nulls bool)
-    AS 'SELECT NULL,FALSE' LANGUAGE SQL STRICT IMMUTABLE SET search_path = pg_catalog, pg_temp;
+    AS $$ SELECT ''::name,FALSE $$
+    LANGUAGE SQL STRICT IMMUTABLE
+    SET search_path = pg_catalog, pg_temp;

tsl/src/compression/compression.c

@@ -46,7 +46,7 @@ static const CompressionAlgorithmDefinition definitions[_END_COMPRESSION_ALGORIT
 	[COMPRESSION_ALGORITHM_DELTADELTA] = DELTA_DELTA_ALGORITHM_DEFINITION,
 };
 
-static const char *compression_algorithm_name[] = {
+static const char compression_algorithm_name[][NAMEDATALEN] = {
 	[_INVALID_COMPRESSION_ALGORITHM] = "INVALID",	   [COMPRESSION_ALGORITHM_ARRAY] = "ARRAY",
 	[COMPRESSION_ALGORITHM_DICTIONARY] = "DICTIONARY", [COMPRESSION_ALGORITHM_GORILLA] = "GORILLA",
 	[COMPRESSION_ALGORITHM_DELTADELTA] = "DELTADELTA",