add row: give option to specify pkey if it's a text field without a default

If you have a table like:

```sql
CREATE TABLE foo(id INTEGER PRIMARY KEY, name TEXT);
```

or

```sql
CREATE TABLE foo(id TEXT PRIMARY KEY DEFAULT ulid(), name TEXT);
```

we should not let you enter the primary key when adding a new row.

But if you have a table like:

```sql
CREATE TABLE foo(id TEXT NOT NULL PRIMARY KEY, name TEXT)
```

we should.