[bugfix] don't trash emoji in profile fields on edit

[Sentynel]

Description

Fix emoji being removed from profile fields when other fields are edited.

There's no trivial way of identifying from the list of emoji in the Account object which ones are used in the DisplayName and which in the Note, as both support emoji. Therefore, this change reparses both of these fields for emoji on any change to the profile. If a new version has been submitted, this is parsed and applied to the account; otherwise we use the current version from the account.

closes #1439
closes #(another issue)

Checklist

Please put an x inside each checkbox to indicate that you've read and followed it: [ ] -> [x]

If this is a documentation change, only the first checkbox must be filled (you can delete the others if you want).

• I/we have read the GoToSocial contribution guidelines.
• I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
• I/we have performed a self-review of added code.
• I/we have written code that is legible and maintainable by others.
• I/we have commented the added code, particularly in hard-to-understand areas.
• I/we have made any necessary changes to documentation.
• I/we have added tests that cover new code.
• I/we have run tests and they pass locally with the changes.
• I/we have run go fmt ./... and golangci-lint run.

[tsmethurst]

Thanks!