chore(gov): move args in gov new proposal constructor

[julienrbrt]

Description

As discussed, it makes more sense to have the 3 strings next to each other (after the addition of title and summary).
As I am doing this for v0.48 here: #14720, it makes sense to do that already for v0.47. So the API break is minimum for v0.48 afterward.

Note: in the backported PR to v0.47.x, we have to cherry-pick the proposer migration from https://github.com/cosmos/cosmos-sdk/pull/13010/files#diff-84dd4933b673594c4303f0a35d9cd93810c49b39a25779abaeb326ebbc34f02fR14.
ref: https://github.com/cosmos/cosmos-sdk/pull/13010/files#r1059373460

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Author Checklist

All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.

I have...

• included the correct type prefix in the PR title
• added ! to the type prefix if API or client breaking change
• targeted the correct branch (see PR Targeting)
• provided a link to the relevant issue or specification
• followed the guidelines for building modules
• included the necessary unit and integration tests
• added a changelog entry to CHANGELOG.md
• included comments for documenting Go code
• updated the relevant documentation or specification
• reviewed "Files changed" and left comments if necessary
• confirmed all CI checks have passed

Reviewers Checklist

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your handle next to the items reviewed if you only reviewed selected items.

I have...

• confirmed the correct type prefix in the PR title
• confirmed ! in the type prefix if API or client breaking change
• confirmed all author checklist items have been addressed
• reviewed state machine logic
• reviewed API design and naming
• reviewed documentation is accurate
• reviewed tests and test coverage
• manually tested (if applicable)

[amaury1093]

LGTM