Merge bitcoin/bitcoin#29625: Several randomness improvements

ce8094246e random: replace construct/assign with explicit Reseed() (Pieter Wuille)
2ae392d561 random: use LogError for init failure (Pieter Wuille)
97e16f5704 tests: make fuzz tests (mostly) deterministic with fixed seed (Pieter Wuille)
2c91330dd6 random: cleanup order, comments, static (Pieter Wuille)
8e31cf9c9b net, net_processing: use existing RNG objects more (Pieter Wuille)
d5fcbe966b random: improve precision of MakeExponentiallyDistributed (Pieter Wuille)
cfb0dfe2cf random: convert GetExponentialRand into rand_exp_duration (Pieter Wuille)
4eaa239dc3 random: convert GetRand{Micros,Millis} into randrange (Pieter Wuille)
82de1b80d9 net: use GetRandMicros for cache expiration (Pieter Wuille)
ddc184d999 random: get rid of GetRand by inlining (Pieter Wuille)
e2d1f84858 random: make GetRand() support entire range (incl. max) (Pieter Wuille)
810cdf6b4e tests: overhaul deterministic test randomness (Pieter Wuille)
6cfdc5b104 random: convert XoRoShiRo128PlusPlus into full RNG (Pieter Wuille)
8cc2f45065 random: move XoRoShiRo128PlusPlus into random module (Pieter Wuille)
8f5ac0d0b6 xoroshiro128plusplus: drop comment about nonexisting copy() (Pieter Wuille)
8924f5120f random: modernize XoRoShiRo128PlusPlus a bit (Pieter Wuille)
ddb7d26cfd random: add RandomMixin::randbits with compile-known bits (Pieter Wuille)
21ce9d8658 random: Improve RandomMixin::randbits (Pieter Wuille)
9b14d3d2da random: refactor: move rand* utilities to RandomMixin (Pieter Wuille)
40dd86fc3b random: use BasicByte concept in randbytes (Pieter Wuille)
27cefc7fd6 random: add a few noexcepts to FastRandomContext (Pieter Wuille)
b3b382dde2 random: move rand256() and randbytes() to .h file (Pieter Wuille)
493a2e024e random: write rand256() in function of fillrand() (Pieter Wuille)

Pull request description:

  This PR contains a number of vaguely-related improvements to the random module.

  The specific changes and more detailed rationale is in the commit messages, but the highlights are:

  * `XoRoShiRo128PlusPlus` (previously a test-only RNG) moves to random.h and becomes `InsecureRandomContext`, which is even faster than `FastRandomContext` but non-cryptographic. It also gets all helper randomness functions (`randrange`, `fillrand`, ...), making it a lot more succinct to use.
  * During tests, **all** randomness is made deterministic (except for `GetStrongRandBytes`) but non-repeating (like `GetRand()` used to be when `g_mock_deterministic_tests` was used), either fixed, or from a random seed (overridden by env var).
  * Several infrequently used top-level functions (`GetRandMillis`, `GetRandMicros`, `GetExponentialRand`) are converted into member functions of `FastRandomContext` (and `InsecureRandomContext`).
  * `GetRand<T>()` (without argument) can now return the maximum value of the type (previously e.g. `GetRand<uint32_t>()` would never return 0xffffffff).

ACKs for top commit:
  achow101:
    ACK ce8094246e
  maflcko:
    re-ACK ce8094246e 🐈
  hodlinator:
    ACK ce8094246e
  dergoegge:
    utACK ce8094246e

Tree-SHA512: 79bc0cbafaf27e95012c1ce2947a8ca6f9a3c78af5f1f16e69354b6fc9b987a28858adf4cd356dc5baf21163e9af8dcc24e70f8d7173be870e8a3ddcdd47c02c

test/sanitizer_suppressions/ubsan

@@ -56,7 +56,8 @@ unsigned-integer-overflow:CBlockPolicyEstimator::processBlockTx
 unsigned-integer-overflow:TxConfirmStats::EstimateMedianVal
 unsigned-integer-overflow:prevector.h
 unsigned-integer-overflow:EvalScript
-unsigned-integer-overflow:xoroshiro128plusplus.h
+unsigned-integer-overflow:InsecureRandomContext::rand64
+unsigned-integer-overflow:InsecureRandomContext::SplitMix64
 unsigned-integer-overflow:bitset_detail::PopCount
 implicit-integer-sign-change:CBlockPolicyEstimator::processBlockTx
 implicit-integer-sign-change:SetStdinEcho
@@ -73,4 +74,6 @@ shift-base:arith_uint256.cpp
 shift-base:crypto/
 shift-base:streams.h
 shift-base:FormatHDKeypath
-shift-base:xoroshiro128plusplus.h
+shift-base:InsecureRandomContext::rand64
+shift-base:RandomMixin<*>::randbits
+shift-base:RandomMixin<*>::randbits<*>