Add collection import panel with documentation (PP-3862)

[jonathangreen]

Description

Adds an import panel to CollectionImportButton for collections whose protocol supports import:

• Dynamic button label and style: Button shows "Queue Full Re-import" when force is checked, making the heavier action visually distinct
• Context-aware success messages: Regular imports note that new/updated items will appear; force re-imports note that all items will be re-processed and it may take longer
• Compact description below the controls using the standard description class, with a "More details" toggle for full documentation

Motivation and Context

PP-3862 — Add description to collection Import function in Collection Manager.

How Has This Been Tested?

• All 19 Jest tests pass (npm run test-jest-file tests/jest/components/CollectionImportButton.test.tsx)
• ESLint and Prettier pass via pre-commit hooks

Checklist:

• I have updated the documentation accordingly.
• All new and existing tests passed.

[tdilauro]

Nice!

[tdilauro]

Very minor: This is the third time I've seen "Force full re-import" in the mainline code. Might be handy to DRY it out with variable containing the label text and interpolate that where needed. Could do similar with the default import labels.

const IMPORT_DEFAULT_LABEL_TEXT = "Queue Import";
const IMPORT_FORCED_FULL_LABEL_TEXT = "Force full re-import";
...
          // button text
          {IMPORT_FORCED_FULL_LABEL_TEXT}
...
      // description text
      <p className="description">
        Queue Import picks up new and changed items. Check{" "}
        <strong>{IMPORT_FORCED_FULL_LABEL_TEXT}</strong> to re-process everything.
      </p>
...
          // detail
          <dt>{IMPORT_FORCED_FULL_LABEL_TEXT}</dt>
...