refactor: solid personal bests modal (@d1rshan)

[d1rshan]

• migrates personal best modal to solidjs
• also fixes ux issues in personal bests modal #7998

[d1rshan]

Hey @Miodec, what do you think of showing mode2 on every row with full opacity on the first row of each group and lower opacity on the rest? (or maybe showing it on hover)

like this (ie showing on every row with lower opacity):

If neither works for you, I can keep the current behaviour. The reason I'm asking is that the Table component makes the existing sticky approach bit awkward without modifying it or using a raw <table>.