Add transient storage slot support in StorageSlot.sol (#4980)

Co-authored-by: ernestognw <ernestognw@gmail.com>

contracts/utils/README.adoc

@@ -29,7 +29,7 @@ Miscellaneous contracts and libraries containing utility functions you can use t
  * {Strings}: Common operations for strings formatting.
  * {ShortString}: Library to encode (and decode) short strings into (or from) a single bytes32 slot for optimizing costs. Short strings are limited to 31 characters.
  * {SlotDerivation}: Methods for deriving storage slot from ERC-7201 namespaces as well as from constructions such as mapping and arrays.
- * {StorageSlot}: Methods for accessing specific storage slots formatted as common primitive types.
+ * {StorageSlot}: Methods for accessing specific storage slots formatted as common primitive types. Also include primitives for reading from and writing to transient storage (only value types are currently supported).
  * {Multicall}: Abstract contract with an utility to allow batching together multiple calls in a single transaction. Useful for allowing EOAs to perform multiple operations at once.
  * {Context}: An utility for abstracting the sender and calldata in the current execution context.
  * {Panic}: A library to revert with https://docs.soliditylang.org/en/v0.8.20/control-structures.html#panic-via-assert-and-error-via-require[Solidity panic codes].