Fix color control of plotScoreHeatmap when 'normalize=TRUE'

[dtm2451]

Per #197

Bug Fix: This PR ensures that when users supply their own color map to the plotScoreHeatmap() function, it will be used regardless of whether normalize was set to TRUE.

New Feature: Also gives users expanded control over their legend by newly allowing override of SingleR's default strategies for filling the pheatmap inputs breaks, legend_breaks, and legend_labels.

ToDo:

• [x] add test
• [x] double-check the other pheatmap inputs for similar overrides, and fix if makes sense
• [x] roxygenize

[dtm2451]

Double-checked other pheatmap inputs that we explicitly touch in the function. All the ones already recorded as inputs are good now, but there 3 currently touched "siltently": breaks, legend_breaks, legend_labels.

If I remember correctly, the plan was to give all of these as explicit inputs so that they could be documented for the user, and I've done that in my last commit.

Also, I might need to rely on you @LTLA to get the updated man pages built. I'm having a bit of trouble getting a proper SingleR dev environment set up at the moment. (Bioconductor hosted devel docker image fails at installing Rcpp, so... can't install SingleR or SingleR deps.) Still working on a solution here, but I can't run R CMD CHECK, roxygen2::roxygenize(), or even test things locally in the meantime.

[LTLA]

LGTM, I just did some minor editing of the doc strings.

[LTLA]

I'm just going to merge and ignore the CI issues; can't do much about those.