This subchapter provides for an action by which persons convicted of crimes they did not commit and persons serving illegal sentences may obtain collateral relief. The action established in this subchapter shall be the sole means of obtaining collateral relief and encompasses all other common law and statutory remedies for the same purpose that exist when this subchapter takes effect, including habeas corpus and coram nobis. This subchapter is not intended to limit the availability of remedies in the trial court or on direct appeal from the judgment of sentence, to provide a means for raising issues waived in prior proceedings or to provide relief from collateral consequences of a criminal conviction. Except as specifically provided otherwise, all provisions of this subchapter shall apply to capital and noncapital cases.