Add themeable ItemBitstreamsComponent

[AbhinavS96]

Description

Added new ThemedItemEditBitstreamComponent.

Instructions for Reviewers

List of changes in this PR:

• New components
  • ThemedItemBitstreamComponent

For the themed components:

• Set the theme to custom theme in config.yml
• Uncomment the CustomEagerThemeModule in src/themes/eager-themes.module.ts
• Test if the new components in the custom theme folder can be themed

Checklist

• My PR is created against the main branch of code (unless it is a backport or is fixing an issue specific to an older branch).
• My PR is small in size (e.g. less than 1,000 lines of code, not including comments & specs/tests), or I have provided reasons as to why that's not possible.
• My PR passes ESLint validation using npm run lint
• My PR doesn't introduce circular dependencies (verified via npm run check-circ-deps)
• My PR includes TypeDoc comments for all new (or modified) public methods and classes. It also includes TypeDoc for large or complex private methods.
• My PR passes all specs/tests and includes new/updated specs or tests based on the Code Testing Guide.
• My PR aligns with Accessibility guidelines if it makes changes to the user interface.
• My PR uses i18n (internationalization) keys instead of hardcoded English text, to allow for translations.
• My PR includes details on how to test it. I've provided clear instructions to reviewers on how to successfully test this fix or feature.
• If my PR includes new libraries/dependencies (in package.json), I've made sure their licenses align with the DSpace BSD License based on the Licensing of Contributions documentation.
• If my PR includes new features or configurations, I've provided basic technical documentation in the PR itself.
• If my PR fixes an issue ticket, I've linked them together.

[github-actions]

Hi @AbhinavS96,
Conflicts have been detected against the base branch.
Please resolve these conflicts as soon as you can. Thanks!

[pzlakowski]

Checklist:

• I have followed Theme guidelines
• I have checked whenever stylesheet is adjustable
• I have checked whenever component html is adjustable
• I have checked on current main with merge
• ESLint

Nitpicks:

1. There are ESLint errors to fix, npm run lint-fix will fix them

/app/src/themes/custom/app/item-page/edit-item-page/item-bitstreams/item-bitstreams.component.ts
  22:3  error    Standalone imports should be sorted alphabetically              
  35:3  error    Unnecessary explicit standalone declaration of the @Component decorator should be removed  dspace-angular-ts/no-default-standalone-valu

2. In my opinion I would add commented out templateUrl and styleUrls like it is done in other custom components. I think it makes theme components more discoverable for new contributors e.g.:

@Component({
  selector: 'ds-themed-item-page',
  // styleUrls: ['./item-page.component.scss'],
  styleUrls: ['../../../../../app/item-page/simple/item-page.component.scss'],
  // templateUrl: './item-page.component.html',
  templateUrl: '../../../../../app/item-page/simple/item-page.component.html',
})

3. There is also a small typo for naming stylesheet:

src/themes/custom/app/item-page/edit-item-page/item-bitstreams/item-bitstream.component.scss

It should be named item-bitstreams.component.scss.

4. There is merge conflict to resolve but it is just imports part to fix