Remove redundant HTML map classes

The `map` class is applied to the map element by LeafletJS; using it in
the container led to hacks like adding an `inline` class to fix the fact
that the container was using the `height` rule of the `.map` elements.

Even though we don't add styles for them, I'm adding the `budgets-map`
and `budget-investments-map` HTML classes so these elements can still be
easily selected with CSS and JavaScript.

app/components/budgets/investments/map_component.html.erb

@@ -1,3 +1,3 @@
-<div class="map">
+<div class="budget-investments-map">
   <%= render_map(map_location, investments_coordinates: coordinates) %>
 </div>

app/components/budgets/investments/map_component.rb

@@ -1,5 +1,6 @@
 class Budgets::Investments::MapComponent < ApplicationComponent
   attr_reader :heading, :investments
+  delegate :render_map, to: :helpers
 
   def initialize(investments, heading:)
     @investments = investments

app/components/budgets/map_component.html.erb

@@ -1,4 +1,4 @@
-<div class="map inline">
+<div class="budgets-map">
   <h2><%= t("budgets.index.map") %></h2>
   <%= render_map(nil, investments_coordinates: coordinates) %>
 </div>