Implement S/T Storage getters/setters and call_data_load, return_data_copy hostfns

[LucasGrasso]

Partially addresses #2653

• [n] y/n | Does it introduce breaking changes?
• [n] y/n | Is it dependent on a specific version of cargo-contract or pallet-revive?

Description

Implements the following host fns:

• set_storage - Implementing set_storage_or_clear for normal storage
• get_storage - Implementing get_storage_or_zero for normal storage
• set_transient_storage - Implementing set_storage_or_clear for transient storage
• get_transient_storage - Implementing get_storage_or_zero for transient storage
• call_data_load
• return_data_copy

[LucasGrasso]

Hey @cmichi @davidsemakula, I would appreciate your thoughts on the following:

Related to Storage functions:

• Currently I'm defining functions for transient and normal storage. I think its more dev friendly than having to set the flags manually.
• Currently I am setting key to be an U256 and value to be [u8;32]. I've been thinking to have a key be any type that implements scale::Encode and that can be encoded to 32-bytes and value to implement Storeable + Default, so to turn to the default value when get_storage_or_zero returns [0,32]. I think this would be great for developers but it implies creating specific functions for clearing a key. (Something like https://github.com/LucasGrasso/ink/pull/1/files)

Related to return_data_copy:

• Should I return a Vec and own the buffer or just make the user pass a buffer?