[9.x] Fix parsing config('database.connections.pgsql.search_path')

[derekmd]

Fixes #41062

e.g., Config value 'test-db' was being parsed as set search_path to "test", "db" instead of set search_path to "test-db"

9.x renamed config('database.connections.pgsql.schema') to config('database.connections.pgsql.search_path') and introduced special handling if the config value is a string containing many segments. The originating PR has some examples. However the given PostgresConnector regex doesn't consider the full range of characters allowed in a schema or variable name - specifically '-' and accented characters.

Replace the 'search_path' regex alphanumeric-only allowlist of characters with a blocklist of delimiters when config('database.connections.pgsql.search_path') is a string value. Technically Postgres does allow our config delimiter characters (spaces, comma, quotes) in symbols so an array configuration can instead be used for such schema names. (However non-wrapping single/double quote characters in such array configs still aren't supported.)

return [
    'default' => env('DB_CONNECTION', 'mysql'),
    'connections' => [
        'pgsql' => [
            'search_path' => [
                "'public'",
                '"$user"',
                'containing commas, and spaces'
                // 'can\'t name schema with "inner quotes"'
            ],

set search_path to "public", "$user", "containing commas, and spaces"

---

• Roll methods testPostgresSearchPathCommaSeparatedValueSupported() & testPostgresSearchPathVariablesSupported() into testPostgresSearchPathIsSet() with the fuller coverage provideSearchPaths() data set.
• testPostgresSearchPathArraySupported() is repurposed to show config('database.connections.pgsql.schema') from versions < 9.x is used when the 'search_path' config key is absent.
• Fix PostgresConnector::quoteSearchPath() parameter docblock since passing in a string value would throw an exception for being un-Countable. Its only use is being passed parseSearchPath()'s return value which is an array.

[taylorotwell]

Thanks!