Rename `sample_prior` to `sample`

[williambdean]

Would it make sense to have sample_prior be just sample? The idea was to have a similar API to the components which have a method of the same name. However, their workflows are a bit different.

For instance, Prior class:

from pymc_marketing.prior import Prior

dist = Prior("Normal")
samples = dist.sample_prior()
# purposed alternative
samples = dist.sample()

The HSGP class has a similar workflow to Prior class.

Similar workflow from the components (Saturation, Adstock, Fourier, LinearTrend, etc)

1. sample_prior
2. sample_curve which takes either prior or posterior
3. plot_curve which takes the curve

from pymc_marketing.mmm import LogisticSaturation

saturation = LogisticSaturation()
prior = saturation.sample_prior()
curve = saturation.sample_curve(prior)
saturation.plot_curve(curve)

Maybe there can be same renaming argument for the components as well.

Would be interested to hear thoughts

Related to #1345

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This issue was transferred from pymc-labs/pymc-marketing#1346