Otherwise all proposals/budgets are removed by `CheckAndRemove`
(negative confirmations for collateral txes).

Introduced in PIVX-Project#1826

…ring init

683fd6b [BUG] Set budget best height before reading budget DB during init (random-zebra)

Pull request description:

  Fix a bug Introduced in #1826, which makes the node erase all proposals and finalized budgets, after reading them from the DB during startup (and thus having to ask everything again from the peers).

  **Cause:**
  The budget manager best height is set after reading the budgetdb.
  As non-dry runs of `CBudgetDB::Read` include a call to `CheckAndRemove()` at the end (to delete expired objects), the manager's best-height needs to be already set.

ACKs for top commit:
  furszy:
    Good catch, ACK 683fd6b.
  Fuzzbawls:
    utACK 683fd6b

Tree-SHA512: e66dd4e8a33eac7a92559fea545a9d8df5aeda27a8d5e490ab7948733320e2d17e105b66dabcd9603c17503838fe505310b844f52b056cecd58f2038e2901651

…+ MN activation functional test.

9a1e5e2 Including functional test coverage for budget finalization sync process. (furszy)
7222705 Simple masternodes final budget suggest RPC command implementation for regtest-only. (furszy)
f485be4 rename masternodes/budget functional test name to use the tiertwo_xxx prefix. (furszy)
3bffe86 masternodes_governance_basic.py test migrated to use mock time. (furszy)
9fab353 test_framework: implement sync_tiertwo util function (furszy)
58eefbd New functional test masternodes_governance_basic.py, added coverage for: (furszy)
2038f2f added test coverage for the following masternode status: expiration, re initialization after expiration, removal, re initialization after removal and collateral spent. (furszy)
4e3d7a3 Move masternodes consensus time definitions to .cpp . (furszy)
b598734 new masternode activation functional test :) . (furszy)
ee44f0c CMasternode added missing internal cs locks. (furszy)
8414747 regtest-only: enable different ports usage for MNs. (furszy)
84dca1a end spork message to let the remote peer know when the sporks broadcast ends. (furszy)
6ed644e Added regtest support for masternode validation values: min confirmations, min ping time, min mnb time, expiration time, removal time. (furszy)
cd7bb34 Introducing new tier two network initial sync architecture. (furszy)
c7b03c0 refactor: abstracted out ProcessGetMNList from CMasternodeMan::ProcessMesssage. (furszy)
4a67a4b refactored ProcessSpork code into ProcessSporkMsg and ProcessGetSporks. (furszy)

Pull request description:

  -- Only running on regtest --

  Covering the following points:
  #### 1) A new synchronization structure for the tier two network.
  It has no redundant checks nor redundant requests (there by less network bloat, faster synchronization) and the code is by far more readable and maintainable than the previous version.

  #### 2) Tier two network regtest support.
  Adding Masternodes and Governance capabilities to the regtest network.

  #### 3) Sync and masternode activation test.
  Functional test validating the correct operation of the tier two network sync and the masternode broadcasting & activation process.

  #### TODO:
  * Clean peer state on peer disconnection (connect signal)
  * Spam filter + spam functional test.
  * Not responding peers timeout test + spam functional test.
  * Sporks broadcasting end message (currently it's using the SPORK_INVALID as end message).
  * Data verification from several peers (currently running, only need to implement a sync threshold to move to the next level) + spam functional test.
  * Further decoupling from the old structure.
  * Previous version cleanup.

  ------------
  Have pushed it under WIP to be able to test other great PRs like #1826.

ACKs for top commit:
  random-zebra:
    Left few more comments (mostly around the use of mocktime which seems a bit funky), but they can be addressed in a later PR, so ACK 9a1e5e2
  Fuzzbawls:
    ACK 9a1e5e2

Tree-SHA512: 0808b26d997d6ee76a6c0217e0321a7dbcf3a4a42d25dd142bd84058f486a9ba19868269f755eb10e05cfea41a8532e0d88593bfc4dbc957fd480e8ea7e6d7eb