[Feature/Improvement] Color code workouts

[a-mabe]

Purpose: As a user, I want to be able to color code workouts.

More details:

Potentially add color picker: https://pub.dev/packages/flutter_material_color_picker

Acceptance Criteria:

• When creating (or editing) a workout, the user can select a color to label the workout.
• Color is used to set background color on the workout's list tile on the homepage and also when viewing the workout.

[alastairrmcneill]

Heya @a-mabe, do you want the colour of the workout to influence the Work = green and Rest = Red colour when running the workout?

[a-mabe]

Hi @alastairrmcneill, just when viewing the workouts on the homescreen and in the view workout screen itself, like these mockups:

Likely would need to add a color picker during workout creation: https://pub.dev/packages/flutter_material_color_picker

And another DB column:

CREATE TABLE IF NOT EXISTS WorkoutTable(id TEXT PRIMARY KEY,
            title TEXT,
            numExercises INTEGER,
            exercises TEXT,
            ...
            workoutColor TEXT // Could save color name, hex value, etc.

Might also have to migrate the existing DB entries so as to not affect existing users.

[alastairrmcneill]

@a-mabe I've created the PR for this issue, let me know if there are any issues with the 2 PRs open at the same time

[alastairrmcneill]

Ah wait hold on, I forgot to ask you to assign it to me. Hope that doesn't cause any issues?

[a-mabe]

No worries @alastairrmcneill, I will assign the issue now. I put the issues in the In Review column so they're on my todo list

[a-mabe]

Closed in #71. Thank you @alastairrmcneill for the contribution!