M3-5546: IP address font color on Firefox in dark mode (#8008)

## Description

Previously, if you go to any Linode Detail page on Firefox in dark mode, the font color for "IP Addresses" and "SSH Access" should be white but instead, it's showing up as black.

This is due to a known Firefox bug that will decide that a font is colored if it contains SVG glyphs (which surprise, Source Code Pro does). The latest release should've fixed this issue but the font is still showing up as black for me after updating the files.

After some sleuthing, I decided to test out [Ubuntu Monospace](https://design.ubuntu.com/font/) as an alternative to Source Code Pro. I tested the font color on Chrome, Firefox, Safari, Edge, Opera, and Vivaldi with no issues.

**Links:**
- [GitHub issue with more details](adobe-fonts/source-code-pro#248)
- [List of Ubuntu Monospace font files](https://google-webfonts-helper.herokuapp.com/fonts/ubuntu-mono?subsets=latin)

## How to test

- On `develop`, use Firefox and go to any Linode Detail page in dark mode to verify the problem
- The font color should now be white after checking out this PR

packages/manager/public/fonts/fonts.css

@@ -37,16 +37,13 @@
   text-rendering: optimizeLegibility;
 }
 
-/* Webfont: SourceCodePro-Regular */
+/* Webfont: UbuntuMono */
 @font-face {
-  font-family: 'SourceCodePro';
+  font-family: 'UbuntuMono';
   src: 
-    /* IE6-IE8 */ url('fonts/SourceCodePro-Regular.ttf.woff2')
-      format('woff2'),
-    /* Modern Browsers */ url('fonts/SourceCodePro-Regular.ttf.woff')
-      format('woff'),
-    /* Modern Browsers */ url('fonts/SourceCodePro-Regular.ttf')
-      format('truetype');
+    /* IE6-IE8 */ url('fonts/UbuntuMono-Regular.woff2') format('woff2'),
+    /* Modern Browsers */ url('fonts/UbuntuMono-Regular.woff') format('woff'),
+    /* Modern Browsers */ url('fonts/UbuntuMono-Regular.ttf') format('truetype');
   font-style: normal;
   font-weight: normal;
   text-rendering: optimizeLegibility;

packages/manager/src/components/LinodeCLIModal/LinodeCLIModal.tsx

@@ -25,7 +25,7 @@ const useStyles = makeStyles((theme: Theme) => ({
     lineHeight: 1,
     padding: theme.spacing(),
     whiteSpace: 'nowrap',
-    fontFamily: '"SourceCodePro", monospace, sans-serif',
+    fontFamily: '"UbuntuMono", monospace, sans-serif',
     wordBreak: 'break-all',
     position: 'relative',
     width: '100%',

packages/manager/src/features/Databases/DatabaseDetail/DatabaseEntityDetail.tsx

@@ -323,7 +323,7 @@ const useBodyStyles = makeStyles((theme: Theme) => ({
   },
   code: {
     color: theme.cmrTextColors.tableStatic,
-    fontFamily: '"SourceCodePro", monospace, sans-serif',
+    fontFamily: '"UbuntuMono", monospace, sans-serif',
   },
 }));
 

packages/manager/src/features/linodes/LinodeEntityDetail.tsx

@@ -644,8 +644,11 @@ const useAccessTableStyles = makeStyles((theme: Theme) => ({
   },
   code: {
     color: theme.cmrTextColors.tableStatic,
-    fontFamily: '"SourceCodePro", monospace, sans-serif',
+    fontFamily: '"UbuntuMono", monospace, sans-serif',
     position: 'relative',
+    '& div': {
+      fontSize: 15,
+    },
   },
   copyCell: {
     width: 36,