Feature: TransactionContext, InstructionContext and BorrowedAccount

[Lichtso]

#21882 and #21927 are preparations for this PR to remove the Rc from Refcell<AccountSharedData> in the program-runtime because Rc can not be serialized.

Problem

• KeyedAccount does not validate self.is_writable() before modification
• As the name suggests, KeyedAccount works by using Pubkey instead of an index (in instruction and in transaction)
• KeyedAccount and AccountInfo are two redundant implementations of nearly the same interface

Summary of Changes

As proposed for ABIv2 (#19191):

• Adds TransactionContext to outsource the accounts, invoke_stack and return_data properties of InvokeContext
• Adds InstructionContext which will replace invoke_context::StackFrame
• Adds BorrowedAccount which will replace only KeyedAccount at first and later also AccountInfo
• Redirects the usage of accounts in InvokeContext through TransactionContext.
• Moves the types TransactionAccount and InstructionAccount into transaction_context.rs.

Replacement of other runtime structs and the encoding and the new BPF loader will come later.
This is only about the interfaces for the runtime and program tests for now, so that we can start migrating them.

Open issues / up to discussion:

• BorrowedAccount is a RefMut, so the user won't be able to borrow the same account multiple times even if they don't want to modify any. But of course, the user can have multiple references to one BorrowedAccount and also wrap it in a RefCell. I don't think that introducing a BorrowedAccountReadonly is necessary.
• Account reallocation interface: Copy the one from AccountInfo?

Fixes #

[codecov]

Codecov Report

Merging #21706 (5de6b8c) into master (cc947ca) will decrease coverage by 0.0%.
The diff coverage is 74.7%.

@@            Coverage Diff            @@
##           master   #21706     +/-   ##
=========================================
- Coverage    81.2%    81.2%   -0.1%     
=========================================
  Files         519      520      +1     
  Lines      145734   145929    +195     
=========================================
+ Hits       118448   118534     +86     
- Misses      27286    27395    +109