Updated all SOAP API clients to be based on API v52.0 WSDLs.
Updated the API version used for primary communication with Salesforce APIs to 52.0.
Added 52.0 as an available API version number for configured connections.
Updated metadata.xsd used for validation and completion in metadata XML files to API v52.0.
Updated the OST version number to prompt regeneration for system API changes in API v52.0.
Added apexTestAccess and release properties to the JSON schema for sfdx-project.json files.
Updated Visualforce, Aura, and LWC components, functions, modules, etc., for Summer '21.
Updated the bundled SLDS to 2.15.8.
Updated all integrated API documentation.
Added XML file type associations for new metadata type file extensions.