feat(curriculum): introduce let and const earlier (#43133)

* fix: move "Explore Differences Between..." to basic JS, update seed and tests

* fix: resequence "Declare String Variables"

* fix: move "Declare a Read-Only Variable..." to basic JS, update seed and tests

* fix: revert changes to non-English "Explore Differences Between..." test text

* fix: revert test strings, solutions, and seeds for non-English challenges

* fix: update "Declare String Variables" description

* fix: sync quotation marks in description and seed

* fix: modify note in "Declare a Read-Only..." challenge

* fix: update operator and compound assignment challenges

* fix: update string challenges

* fix: update array and array method challenges

* fix: update function and scope challenges, resequence slightly

* fix: "Word Blanks" solution

* fix: add spacing to seed

* fix: concatenating += challenge spacing

* fix: appending variables to strings spacing

* fix: find the length of a string spacing

* fix: removed instances of removedFromMyArray = 0

* fix: switch challenges

* fix: function argument and param spacing

* fix: update counting cards, object challenges, and record collection

* fix: finish rest of Basic JS section

* fix: introducing else statements solution

* fix: update spacing and wording

* fix: update wording for const challenge

* fix: update functional programming challenges

* fix: intermediate algorithms and cert challenges

* fix: revert some spacing and remove comments for fp challenge solutions

* feat: add notes with links to moved let and const challenges in first two es6 challenges

* fix: update es6 intro text

* Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md

Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>

* Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md

Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>

* Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/global-scope-and-functions.md

Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>

* Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md

Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>

* Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md

Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>

* Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md

Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>

* Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/declare-a-read-only-variable-with-the-const-keyword.md

Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>

* fix: concatenating strings with plus operator seed

* fix: add comments back to Declare a Read-Only Variable... seed

* feat: add es6 to basic javascript redirect tests for let and const challenges

* fix: revert "Concatenating Strings with Plus Operator" seed

* fix: move test file to cypress/integration/learn/redirects, separate redirect tests

Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>

curriculum/challenges/_meta/basic-javascript/meta.json

@@ -29,6 +29,10 @@
       "56533eb9ac21ba0edf2244a9",
       "Initializing Variables with the Assignment Operator"
     ],
+    [
+      "bd7123c9c444eddfaeb5bdef",
+      "Declare String Variables"
+    ],
     [
       "56533eb9ac21ba0edf2244aa",
       "Understanding Uninitialized Variables"
@@ -37,6 +41,14 @@
       "56533eb9ac21ba0edf2244ab",
       "Understanding Case Sensitivity in Variables"
     ],
+    [
+      "587d7b87367417b2b2512b3f",
+      "Explore Differences Between the var and let Keywords"
+    ],
+    [
+      "587d7b87367417b2b2512b41",
+      "Declare a Read-Only Variable with the const Keyword"
+    ],
     [
       "cf1111c1c11feddfaeb3bdef",
       "Add Two Numbers with JavaScript"
@@ -93,10 +105,6 @@
       "56533eb9ac21ba0edf2244b2",
       "Compound Assignment With Augmented Division"
     ],
-    [
-      "bd7123c9c444eddfaeb5bdef",
-      "Declare String Variables"
-    ],
     [
       "56533eb9ac21ba0edf2244b5",
       "Escaping Literal Quotes in Strings"
@@ -201,6 +209,10 @@
       "56533eb9ac21ba0edf2244bd",
       "Passing Values to Functions with Arguments"
     ],
+    [
+      "56533eb9ac21ba0edf2244c2",
+      "Return a Value from a Function with Return"
+    ],
     [
       "56533eb9ac21ba0edf2244be",
       "Global Scope and Functions"
@@ -213,10 +225,6 @@
       "56533eb9ac21ba0edf2244c0",
       "Global vs. Local Scope in Functions"
     ],
-    [
-      "56533eb9ac21ba0edf2244c2",
-      "Return a Value from a Function with Return"
-    ],
     [
       "598e8944f009e646fc236146",
       "Understanding Undefined Value returned from a Function"