Add epoxy_mustache()

[gadenbuie]

Closes #91
Closes #92

# The canonical mustache example
epoxy_mustache(
  "Hello {{name}}!",
  "You have just won {{value}} dollars!",
  "{{#in_ca}}",
  "Well, {{taxed_value}} dollars, after taxes.",
  "{{/in_ca}}",
  .data = list(
    name = "Chris",
    value = 10000,
    taxed_value = 10000 - (10000 * 0.4),
    in_ca = TRUE
  )
)
#> Hello Chris!
#> You have just won 10000 dollars!
#> Well, 6000 dollars, after taxes.

# Vectorized over the rows of .data
epoxy_mustache(
    "mpg: {{ mpg }}",
    "hp: {{ hp }}",
    "wt: {{ wt }}\n",
    .data = mtcars[1:2, ]
)
#> mpg: 21
#> hp: 110
#> wt: 2.62
#> 
#> mpg: 21
#> hp: 110
#> wt: 2.875

[codecov-commenter]

Codecov Report

Merging #103 (a4f820c) into main (985a74a) will increase coverage by 0.27%.
The diff coverage is 100.00%.

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@@            Coverage Diff             @@
##             main     #103      +/-   ##
==========================================
+ Coverage   95.43%   95.71%   +0.27%     
==========================================
  Files           8        9       +1     
  Lines         855      886      +31     
==========================================
+ Hits          816      848      +32     
+ Misses         39       38       -1     

Files Changed	Coverage Δ
R/epoxy.R	94.25% <ø> (ø)
R/shiny.R	90.47% <ø> (ø)
R/engines.R	94.11% <100.00%> (+1.31%)	⬆️
R/epoxy_mustache.R	100.00% <100.00%> (ø)
R/utils.R	100.00% <100.00%> (ø)

[github-actions]

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