[mac] make `Frame::ParseInfo` public and unify frame field access (#13543)

This commit refactors MAC frame parsing and field inspection across
the OpenThread stack by making `Frame::ParseInfo`, `RxFrame::ParseInfo`,
and `TxFrame::ParseInfo` public and deprecating/removing individual
getter methods directly on `Frame`.

Previously, `Frame` provided dozens of separate getter methods
(`GetDstAddr()`, `GetSrcAddr()`, `GetDstPanId()`, `GetSrcPanId()`,
`GetSecurityLevel()`, `GetKeyIdMode()`, `GetFrameCounter()`,
`GetCommandId()`, `GetPayload()`, `Find<IeType>()`, etc.). Calling
these methods repeatedly on the same frame resulted in multiple
parsing passes over the PSDU buffer. Furthermore, callback handlers
across `SubMac`, `Mac`, `MeshForwarder`, and various schedulers had to
re-query individual fields or maintain partial state independently.

This commit unifies frame parsing into a single-pass model:
- `ParseInfo` extracts and caches all relevant frame header fields,
  addresses, PAN IDs, security attributes, Header IEs, and payload/header
  boundaries during a single parse pass.
- Frame parsing and validation can be done incrementally using
  `ParseMode` (`kParseAddrFields`, `kParseSecurityHeader`, or
  `kParseFully`).
- Passing `ParseInfo` across layer boundaries eliminates redundant
  parsing operations and simplifies code across the codebase.