refactor: Move some methods inside TX Factory (backport cosmos#9421) (c…

…osmos#10039)

* refactor: Move some methods inside TX Factory (cosmos#9421)

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Putting some things inside the factory (which was very anemic struct) has helped me to understand the flow. Feel free to merge if you see some benefit.

closes: #XXXX

---

Before we can merge this PR, please make sure that all the following items have been
checked off. If any of the checklist items are not applicable, please leave them but
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- [ ] Targeted PR against correct branch (see [CONTRIBUTING.md](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
- [ ] Code follows the [module structure standards](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules/structure.md).
- [ ] Wrote unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [ ] Updated relevant documentation (`docs/`) or specification (`x/<module>/spec/`)
- [ ] Added relevant `godoc` [comments](https://blog.golang.org/godoc-documenting-go-code).
- [ ] Added a relevant changelog entry to the `Unreleased` section in `CHANGELOG.md`
- [ ] Re-reviewed `Files changed` in the Github PR explorer
- [ ] Review `Codecov Report` in the comment section below once CI passes

(cherry picked from commit e17be87)

* Update CHANGELOG.md

Co-authored-by: Jonathan Gimeno <jgimeno@gmail.com>
Co-authored-by: Robert Zaremba <robert@zaremba.ch>

CHANGELOG.md

@@ -52,7 +52,11 @@ Ref: https://keepachangelog.com/en/1.0.0/
 ### Bug Fixes
 
 + [\#9965](https://github.com/cosmos/cosmos-sdk/pull/9965) Fixed `simd version` command output to report the right release tag.
-
++ 
+### API Breaking Changes
+* (client/tx) [\#9421](https://github.com/cosmos/cosmos-sdk/pull/9421/) `BuildUnsignedTx`, `BuildSimTx`, `PrintUnsignedStdTx` functions are moved to
+  the Tx Factory as methods.
+
 ## [v0.43.0](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.43.0) - 2021-08-10
 
 ### Features
@@ -142,7 +146,6 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (x/capability) [\#9836](https://github.com/cosmos/cosmos-sdk/pull/9836) Removed `InitializeAndSeal(ctx sdk.Context)` and replaced with `Seal()`. App must add x/capability module to the begin blockers which will assure that the x/capability keeper is properly initialized. The x/capability begin blocker must be run before any other module which uses x/capability.
 
 
-
 ### State Machine Breaking
 
 * (x/{bank,distrib,gov,slashing,staking}) [\#8363](https://github.com/cosmos/cosmos-sdk/issues/8363) Store keys have been modified to allow for variable-length addresses.