Invert the chart direction with RTL languages

[delia-cheminot]

Description

When the UI is set to a RTL language (Urdu), the chart time should go from right to left. This inverts all data when in RTL, as well as the graph ui (chart axis, current level info, side of the page for bar charts).

new helper : chart_mirror.dart

Main chart :

• the x range, the level and blood-test spots, and the "now" line are mirrored
• the y-axis labels move from the left side to the right side in RTL
• the date labels rotate the other way
• the "now" label is aligned bottom-left and wrapped in RTL characters
• paddings use EdgeInsetsDirectional (start/end) instead of left/right
• the pan gesture is inverted, so a drag moves in the correct direction

Baby charts :

• mirrors its spots + now indicator
• the now label now uses a directional FractionallySizedBox

Bar charts :

• buildBarGroups reverses the bar order
• the blood test bar chart aligns to the end in RTL, its labels rotate the other way, and its tooltips use the context text direction

Boy scout : add demo mode as a secret setting for an easier dev experience.

Dependency

m3e_core on my fork to fix the connected buttons (ends rounded on the wrong side in LTR)

Type of change

• Bug fix (non-breaking change which fixes an issue)

Screenshots:

[github-actions]

Line-change breakdown

Category	Files	Added	Deleted	Net
Generated	1	9	8	+1
i18n	0	0	0	+0
Test	0	0	0	+0
Code	14	872	109	+763
Total	15	881	117	+764