Add an optional surrounding key for the pattern patch

[TheBearodactyl]

this makes it easier to only patch one instance of a piece of code when there's more than one in the target file with a pattern patch as opposed to needing a regex patch. For example:

lovely.toml:

[[patches]]
[patches.pattern]
target = "cardarea.lua"
pattern = "card:highlight(false)"
surrounding = { before = "end", after = "if self == G.hand and G.STATE == G.SELECTING_HAND then" }
position = "at"
payload = '''
if card then
    card:highlight(false)
end
'''
match_indent = true

Turns this:

cardarea.lua:

...
    if #self.highlighted >= self.config.highlighted_limit then
        card:highlight(false)
    else
...
        end
    end
    card:highlight(false)
    if self == G.hand and G.STATE == G.SELECTING_HAND then
...

into this:
cardarea.lua:

...
    if #self.highlighted >= self.config.highlighted_limit then
        card:highlight(false) -- Unaffected
    else
...
        end
    end
    if card then
        card:highlight(false) -- Had the patch applied
    end
    if self == G.hand and G.STATE == G.SELECTING_HAND then
...