Adding weekly visualization function for flagged data

[juandlt-csu]

This PR addresses issue #39 and introduces some simple changes:

• Created functional methods for visualizing flagged data.
  • Developed a separate function for daily visualization: generate_daily_flag_plots()
  • Developed a separate function for weekly visualization: generate_weekly_flag_plots()
    • This works, but I would classify it as buggy. Sometimes the plot will not filter properly (I think) and as a result not display all the days in the week in the plot. I explored why this happens (NA values, dates between months) but I couldn't figure it out. Something to look into for the future.
  • Developed function to stack the results from these functions: weekly_daily_flag_plots()
• Fixed a bug related to the full join of field notes.
  • Filtered field notes by site before joining them to the rest of the data. Weird things were happening without this step because of the full_join() step.
• Included a backup weekly visualization method in the scratch folder.

Apologies for the lengthy PR!

[juandlt-csu]

There was a mistake in the code that I want to fix before I leave.