Move the theme change toggle to better place.

[pranshuchittora]

Description

1. The theme change toggle's placement is incorrect as it is being placed at the most important place i.e. top left, ideally it should be place in the top right as it's not the highlight of the product.

2. There's no indication about what the toggle does, which makes not a good UX. We can replace it with something intuitive and self descriptive. 👇🏼

[udasitharani]

I would like to work on this.

[palash-signoz]

@udasitharani sure go for it

[pranay01]

@udasitharani This would also need some UX input.

We were thinking of use what docusaurus uses on its main page https://docusaurus.io/

Though, I not sure on the location it should be put at - we can put at top right corner as it has date time filter and I think theme toggle filter there would be distracting.

Other location is above slack support button - but that also seems not very optimal

Any better position for this?