Added some data retrieval methods to fetch data easily.

[Aniketkhote]

What kind of change does this PR introduce?

feature

What is the current behavior?

To fetch single latest or oldest data currently need to apply order() on created_at field and then single() method to get one also to fetch null, true or false we need to pass in isFilter.

What is the new behavior?

latest() and oldest()

Before

final data = await supabase.from('users').select().order('created_at, ascending: true).single();

Now

final data = await supabase.from('users').select().latest();
or
final data = await supabase.from('users').select().latest('id');

same for oldest.

isNull() , isTrue() and isFalse()

Before

final data = await supabase.from('users').select().isFilter('data', null);

Now

final data = await supabase.from('users').select().isNull('data');
or
final data = await supabase.from('users').select().isTrue('data');
or
final data = await supabase.from('users').select().isFalse('data');

[dshukertjr]

Thanks for the suggestion, but unfortunately we are not adding these new methods.