Add Polish keymap

[fauxpark]

Description

🇵🇱

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[vomindoraan]

Could you bundle the following changes to the Slovak keymap together with this PR, please? I feel it doesn't deserve a PR of its own:

diff --git a/quantum/keymap_extras/keymap_slovak.h b/quantum/keymap_extras/keymap_slovak.h
index 7a02dcfdf..f0bd6ae51 100644
--- a/quantum/keymap_extras/keymap_slovak.h
+++ b/quantum/keymap_extras/keymap_slovak.h
@@ -36,10 +36,10 @@
 // Row 1
 #define SK_SCLN KC_GRV  // ;
 #define SK_PLUS KC_1    // +
-#define SK_LACU KC_2    // ľ
+#define SK_LCAR KC_2    // ľ
 #define SK_SCAR KC_3    // š
 #define SK_CCAR KC_4    // č
-#define SK_TACU KC_5    // ť
+#define SK_TCAR KC_5    // ť
 #define SK_ZCAR KC_6    // ž
 #define SK_YACU KC_7    // ý
 #define SK_AACU KC_8    // á
@@ -141,10 +141,10 @@
  */
 // Row 1
 #define SK_TILD ALGR(SK_PLUS) // ~
-#define SK_CIRC ALGR(SK_LACU) // ^ (dead)
+#define SK_CIRC ALGR(SK_LCAR) // ^ (dead)
 #define SK_BREV ALGR(SK_SCAR) // ˘ (dead)
 #define SK_RNGA ALGR(SK_CCAR) // ° (dead)
-#define SK_OGON ALGR(SK_TACU) // ˛ (dead)
+#define SK_OGON ALGR(SK_TCAR) // ˛ (dead)
 #define SK_GRV  ALGR(SK_ZCAR) // `
 #define SK_DOTA ALGR(SK_YACU) // ˙ (dead)
 #define SK_DACU ALGR(SK_EACU) // ˝ (dead)

I overlooked this when I was reviewing #8561. Even though the lowercase ľ and ť are written with what looks like an acute accent, it's actually a caron (mäkčeň).

[fauxpark]

Good spot