Expand Number to support the full integer range (#6025)

- Refactor Number internals away from int64 to uint64 & a sign flag
  - ctors and accessors return `rep`. Very few things expose
    `internalrep`.
  - An exception is "unchecked" and the new "normalized", which explicitly
    take an internalrep. But with those special control flags, it's easier
    to distinguish and control when they are used.

- For now, skip the larger mantissas in AMM transactions and tests

- Remove trailing zeros from scientific notation Number strings
  - Update tests. This has the happy side effect of making some of the string
    representations _more_ consistent between the small and large
    mantissa ranges.

- Add semi-automatic rounding of STNumbers based on Asset types
  - Create a new SField metadata enum, sMD_NeedsAsset, which indicates
    the field should be associated with an Asset so it can be rounded.
  - Add a new STTakesAsset intermediate class to handle the Asset
    association to a derived ST class. Currently only used in STNumber,
    but could be used by other types in the future.
  - Add "associateAsset" which takes an SLE and an Asset, finds the
    sMD_NeedsAsset fields, and associates the Asset to them. In the case
    of STNumber, that both stores the Asset, and rounds the value
    immediately.
  - Transactors only need to add a call to associateAsset _after_ all of
    the STNumbers have been set. Unfortunately, the inner workings of
    STObject do not do the association correctly with uninitialized
    fields.
  - When serializing an STNumber that has an Asset, round it before
    serializing.
  - Add an override of roundToAsset, which rounds a Number value in place
    to an Asset, but without any additional scale.
  - Update and fix a bunch of Loan-related tests to accommodate the
    expanded Number class.

---------

Co-authored-by: Vito <5780819+Tapanito@users.noreply.github.com>

include/xrpl/protocol/detail/features.macro

@@ -17,7 +17,7 @@
 // Keep it sorted in reverse chronological order.
 
 XRPL_FIX    (BatchInnerSigs,             Supported::yes, VoteBehavior::DefaultNo)
-XRPL_FEATURE(LendingProtocol,            Supported::yes, VoteBehavior::DefaultNo)
+XRPL_FEATURE(LendingProtocol,            Supported::no,  VoteBehavior::DefaultNo)
 XRPL_FEATURE(PermissionDelegationV1_1,   Supported::no,  VoteBehavior::DefaultNo)
 XRPL_FIX    (DirectoryLimit,             Supported::yes, VoteBehavior::DefaultNo)
 XRPL_FIX    (IncludeKeyletFields,        Supported::yes, VoteBehavior::DefaultNo)
@@ -31,7 +31,7 @@ XRPL_FIX    (EnforceNFTokenTrustlineV2,  Supported::yes, VoteBehavior::DefaultNo
 XRPL_FIX    (AMMv1_3,                    Supported::yes, VoteBehavior::DefaultNo)
 XRPL_FEATURE(PermissionedDEX,            Supported::yes, VoteBehavior::DefaultNo)
 XRPL_FEATURE(Batch,                      Supported::yes, VoteBehavior::DefaultNo)
-XRPL_FEATURE(SingleAssetVault,           Supported::yes,  VoteBehavior::DefaultNo)
+XRPL_FEATURE(SingleAssetVault,           Supported::no,  VoteBehavior::DefaultNo)
 XRPL_FIX    (PayChanCancelAfter,         Supported::yes, VoteBehavior::DefaultNo)
 // Check flags in Credential transactions
 XRPL_FIX    (InvalidTxFlags,             Supported::yes, VoteBehavior::DefaultNo)