Support setting a shielded address as refund target

[yito88]

Describe your changes

Closes #4168

Based on #4134

• Diffs: https://github.com/anoma/namada/compare/bat+tiago/feat/ibc-pfm-with-invalid-addrs..yuji/ibc-shielded-refund

Checklist before merging

• If this PR has some consensus breaking changes, I added the corresponding breaking:: labels
  • This will require 2 reviewers to approve the changes
• If this PR requires changes to the docs or specs, a corresponding PR is opened in the namada-docs repo
  • Relevant PR if applies:
• If this PR affects services such as namada-indexer or namada-masp-indexer, a corresponding PR is opened in that repo
  • Relevant PR if applies:

[codecov]

Codecov Report

Attention: Patch coverage is 44.18605% with 600 lines in your changes missing coverage. Please review.

Project coverage is 74.40%. Comparing base (c0b9f68) to head (9ced974).

Files with missing lines	Patch %	Lines
crates/ibc/src/lib.rs	30.71%	185 Missing ⚠️
crates/ibc/src/context/middlewares/pfm_mod.rs	52.63%	180 Missing ⚠️
crates/sdk/src/tx.rs	0.00%	79 Missing ⚠️
crates/sdk/src/masp.rs	22.58%	48 Missing ⚠️
crates/ibc/src/context/nft_transfer_mod.rs	5.26%	36 Missing ⚠️
crates/ibc/src/msg.rs	48.88%	23 Missing ⚠️
crates/ibc/src/context/common.rs	50.00%	14 Missing ⚠️
crates/ibc/src/context/transfer_mod.rs	63.15%	14 Missing ⚠️
crates/sdk/src/rpc.rs	0.00%	12 Missing ⚠️
crates/ibc/src/context/token_transfer.rs	63.63%	8 Missing ⚠️
... and 1 more

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4233      +/-   ##
==========================================
- Coverage   74.59%   74.40%   -0.19%     
==========================================
  Files         342      344       +2     
  Lines      108724   109587     +863     
==========================================
+ Hits        81101    81543     +442     
- Misses      27623    28044     +421     

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