feat: [Week View] Option to set the all day events header row title

[MartimTSilva]

Description

Allow user to set a title for the full day row on week view.
New option name: fullDayHeaderTitle

Checklist

• The title of my PR starts with a Conventional Commit prefix (fix:, feat:, docs: etc).
• I have followed the Contributor Guide when preparing my PR.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation in docs and added dartdoc comments with ///.
• I have updated/added relevant examples in examples or docs.

Breaking Change?

• Yes, this PR is a breaking change.
• No, this PR is not a breaking change.

Related Issues

#308

[marcmacias96]

I need this :c

[MartimTSilva]

I need this :c

You can use my forked solution:
https://github.com/MartimTSilva/flutter_calendar_view/tree/feat/allDayHeaderTitle

[ParthBaraiya]

Hi @MartimTSilva , Thanks for creating this PR. Please fix the merge conflicts and update PR.

[apurva010]

Create and update this PR in #361.