feat(theme-generator): Add possibility to force custom color @angular/material:theme-color

### Feature Description

My problem is that I still can't understand how `@angular/material:theme-color` works. In the terminal, I need to provide colors for primary, secondary, and tertiary. For each one, I specify a single color, like #ff9500, because that's what I want.

`What HEX color should be used to generate the M3 theme? It will represent your primary color palette. (ex. #ffffff) **#005dba**
What HEX color should be used represent the secondary color palette? (Leave blank to use generated colors from Material) **#005dba**
What HEX color should be used represent the tertiary color palette? (Leave blank to use generated colors from Material) **#005dba**`

However, when generating the theme, I see that it creates color palettes, but when I try to get just my color, I use **`--mat-sys-primary`.** Unfortunately, it appears significantly darker (#8c5000), and I don't know which variable the color is actually hidden under. I have the impression that due to the low contrast, it is being artificially darkened. However, I selected the option not to generate mixins with high contrast. I would like to be able to use exactly that color without worrying about contrast. Currently, I am forced to manually change all the system token colors because the generated palette still interferes too much with what I want to achieve, taking away the flexibility I need in this case.

### Use Case

It would be great to be able to specify in the terminal that I want exactly the colors I mention, without any interference.

Beginne mit dem @angular/material:theme-color-Generator und seinen Terminal-Eingabeaufforderungen und vergleiche dann die angeforderten Farben mit dem generierten --mat-sys-primary-Wert. Die Aufgabe ist abgeschlossen, wenn Benutzer die angegebenen Farben exakt verwenden können, ohne dass die generierte Palette oder Kontrastanpassungen sie überschreiben.

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