feat: Improve withdraw-all-rewards UX (backport cosmos#9781) (cosmos#…

…9824)

* feat: Improve withdraw-all-rewards UX (cosmos#9781)

## Description
Related to cosmos#9489, this PR improves the UX when using the `withdraw-all-rewards` command by forcing the broadcast mode to `block` if the chunk size is greater than 0. This will ensure that the transactions do not fail even if the user uses invalid broadcast modes for this command (`sync` and `async`).

---

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(cherry picked from commit 90157fc)

# Conflicts:
#	CHANGELOG.md

* Fix conflict

Co-authored-by: Riccardo Montagnin <[email protected]>
Co-authored-by: Robert Zaremba <[email protected]>

CHANGELOG.md

@@ -54,6 +54,10 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 * [\#9793](https://github.com/cosmos/cosmos-sdk/pull/9793) Fixed ECDSA/secp256r1 transaction malleability.
 
+### CLI Breaking Changes
+
+* [\#9781](https://github.com/cosmos/cosmos-sdk/pull/9781) Improve`withdraw-all-rewards` UX when broadcast mode `async` or `async` is used.
+
 ## [v0.43.0-rc2](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.43.0-rc2) - 2021-07-19
 
 ### Bug Fixes