Adding a shielding fee for normal shielding txs.

[batconjurer]

Describe your changes

Closes #4716

Checklist before merging

• If this PR has some consensus breaking changes, I added the corresponding breaking:: labels
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• If this PR requires changes to the docs or specs, a corresponding PR is opened in the namada-docs repo
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• 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:

[sug0]

overall this is correct, in terms of impl alone. we should check in with @cwgoes that this meets the desired design principles. also, should pitch in some opinion from @murisi about the hw wallet changes required

[brentstone]

Let's get some new reviews here

[brentstone]

Just want to note that the fee must only be taken if the associated tx is successful @sug0