Support glow for text (fixes for #3858)

[SimonDanisch]

Original PR: #3858
This version enables glowwidth/color for WGLMakie as well.

[MakieBot]

Compile Times benchmark

Note, that these numbers may fluctuate on the CI servers, so take them with a grain of salt. All benchmark results are based on the mean time and negative percent mean faster than the base branch. Note, that GLMakie + WGLMakie run on an emulated GPU, so the runtime benchmark is much slower. Results are from running:

using_time = @ctime using Backend
# Compile time
create_time = @ctime fig = scatter(1:4; color=1:4, colormap=:turbo, markersize=20, visible=true)
display_time = @ctime Makie.colorbuffer(display(fig))
# Runtime
create_time = @benchmark fig = scatter(1:4; color=1:4, colormap=:turbo, markersize=20, visible=true)
display_time = @benchmark Makie.colorbuffer(fig)

	using	create	display	create	display
GLMakie	4.36s (4.33, 4.40) 0.02+-	110.73ms (109.17, 114.38) 1.73+-	494.62ms (489.69, 500.35) 3.88+-	8.08ms (8.00, 8.20) 0.07+-	26.10ms (26.00, 26.22) 0.08+-
master	4.37s (4.33, 4.41) 0.02+-	110.17ms (108.77, 113.82) 1.74+-	494.82ms (489.51, 497.87) 2.79+-	7.96ms (7.74, 8.09) 0.12+-	26.12ms (26.03, 26.21) 0.07+-
evaluation	1.00x invariant, -0.01s (-0.53d, 0.34p, 0.02std)	0.99x invariant, 0.56ms (0.33d, 0.55p, 1.73std)	1.00x invariant, -0.21ms (-0.06d, 0.91p, 3.34std)	0.99x invariant, 0.12ms (1.17d, 0.05p, 0.10std)	1.00x invariant, -0.02ms (-0.28d, 0.61p, 0.08std)
CairoMakie	3.58s (3.54, 3.61) 0.03+-	103.28ms (102.38, 104.07) 0.60+-	126.75ms (125.69, 128.43) 0.94+-	7.36ms (7.32, 7.41) 0.04+-	972.71μs (968.69, 981.39) 4.22+-
master	3.69s (3.51, 3.79) 0.12+-	103.70ms (102.53, 105.61) 0.94+-	126.95ms (125.75, 127.75) 0.64+-	7.37ms (7.29, 7.49) 0.08+-	967.78μs (962.21, 974.83) 4.58+-
evaluation	1.03x faster ✓, -0.11s (-1.37d, 0.04p, 0.07std)	1.00x invariant, -0.41ms (-0.52d, 0.35p, 0.77std)	1.00x invariant, -0.21ms (-0.26d, 0.64p, 0.79std)	1.00x invariant, -0.01ms (-0.25d, 0.66p, 0.06std)	0.99x invariant, 4.93μs (1.12d, 0.06p, 4.40std)
WGLMakie	4.50s (4.45, 4.59) 0.05+-	108.76ms (104.69, 117.08) 4.12+-	9.13s (9.03, 9.27) 0.11+-	10.11ms (9.88, 10.37) 0.16+-	73.23ms (70.62, 83.59) 4.64+-
master	4.51s (4.47, 4.54) 0.02+-	106.71ms (104.34, 110.00) 1.87+-	9.19s (9.02, 9.64) 0.20+-	9.99ms (9.89, 10.33) 0.15+-	70.70ms (69.94, 71.96) 0.69+-
evaluation	1.00x invariant, -0.01s (-0.30d, 0.59p, 0.03std)	0.98x invariant, 2.05ms (0.64d, 0.26p, 2.99std)	1.01x invariant, -0.06s (-0.38d, 0.50p, 0.15std)	0.99x invariant, 0.12ms (0.78d, 0.17p, 0.16std)	0.97x invariant, 2.53ms (0.76d, 0.20p, 2.67std)