[Backport] Improve CRUD budgets and content blocks

[microweb10]

References

PR AyuntamientoMadrid#1795

Objectives

• Improve messages of links to go back from budget groups and headings.
• Highlight the budget section in the admin menu.
• Improve explanation texts about content blocks.
• Refactor code to make it more readable.

Visual Changes

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AFTER

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AFTER

Does this PR need a Backport to CONSUL?

Yes

Notes

⚠️ From now on, content blocks are supposed to have only links. If you previously had some other HTML injected by using the content blocks feature, it might not render as it did before ☺️ . If you would like to make more specific changes to the footer or other views check out the docs on creating custom views https://consul_docs.gitbooks.io/docs/en/customization/views_and_styles.html