Enhance cashflow with frequency and projection start date

[janekamata]

ℹ️ Issue

Closes #389

📝 Description

Comprehensively added frequency field to cost and start date to default values

Briefly list the changes made to the code:

1. Created new Frequency enum for cashflow cost
2. Updated cost and default types in front/back end
3. Updated backend tests and routes to include new fields
4. Updated processCashflow functions with new fields
5. Added sorting to local cashflow item lists to fix bug where editing line item reorders them in unclear manner
6. Combined CashEditCost and CashAddCost into one component
7. Added date to cash position component
8. Updated cost card text and added scrolling to line item lists
9. Miscellaneous styling fixes on GrantPage, GrantView, and cashflow

✔️ Verification

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Tested adding/editing

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Test Changes

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🏕️ (Optional) Future Work / Notes

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During stand-up we agreed on the three types of one-time, annual, and annual distributed monthly. However, I wasn't sure how to communicate the last one in a way that made sense to the user, so I currently have it as monthly. During the client meeting, please check if this is needed and also how it should be displayed (both in edit/add and on the card text) so that it is intuitive

I added scrolling to the line item lists but not sure if it's better or not so if we could have some discussion around that as well that would be good. Maybe during next standup

[prooflesben]

I'm sorry to say this but Hessan said the 3 month case is valid and he wants a custom frequency. I would change the frequency from an enum to just the number of months the frequency is since it can be from 1 month to 36 months or 0 months(Could be treated as one time). I would still have the frontend have the dropdown with the options but add a custom option where the user can input how many months they want from 1 to 12 months. (There is a tiny chance we could want things over 12 months like every 18 months but if that case comes up in the future this model of frequency should be able to handle that but we aren;t going to handle it right now in interest of time)