Add meta-data to Excel and iCalendar pre-processed files

An an IAO analyst, I want all files pre-processed files with metadata and stored so that these records are more easily redacted later

**Acceptance Criteria**

**Scenario 1: Index files with a hash **
* GIVEN a file is Excel or iCalendar
* WHEN the file is pre-processed
* THEN the file will be indexed with a hash

**Scenario 2: xxxxxx**
* GIVEN ... (you or your condition)
* WHEN ... (what you do)
* THEN ... (what you see)

**Scenario 3: xxxxxx**
...

**Dependencies? **

Indexing files will be a dependency for future redaction with ML.

**Validation Rules? (If yes, list here)**

**Design**
No UI, so no design required.

**Definition of Ready**

1. [ ] Is there a well articulated User Story?
2. [ ] Is there Acceptance Criteria that covers all scenarios (happy/sad paths)?
3. [ ] If there is a user interface, is there a design?
4. [ ] Does the user story need user research/validation?
5. [ ] Does this User Story needs stakeholder approval?
6. [ ] Design / Solution accepted by Product Owner
7. [ ] Is this user story small enough to be completed in a Sprint? Should it be split?
8. [ ] Are the dependencies known/ understood? (technical, business, regulatory/policy)
9. [ ] Has the story been estimated?

**Definition of Done**

1. [ ] Passes developer unit tests
2. [ ] Passes peer code review
3. [ ] If there's a user interface, passes UX assurance
4. [ ] Passes QA of Acceptance Criteria with verification in Dev and Test
5. [ ] Confirm Test cases built and succeeding
6. [ ] No regression test failures
7. [ ] Test coverage acceptable by Product Owner
8. [ ] Ticket ready to be merged to master or story branch
9. [ ] Developer to list Config changes/ Update documents and designs
10. [ ] Can be demoed in Sprint Review
11. [ ] Tagged as part of a Release
12. [ ] Feature flagged if required
13. [ ] Change Management activities done?

The issue names no files, tests, or entry points. Start by locating the Excel and iCalendar preprocessing paths and clarifying the missing acceptance scenarios and metadata requirements. Done means pre-processed files are stored with a hash index and the agreed behavior is covered by unit and acceptance tests.

Written by the indexing model from the issue text.