GHA/checksrc: expand spellcheck, fix issues found

- codespell: break logic out into its own runnable script. Allowing
  to run it on local machines.
- codespell: install via `pip`, bump to latest version.
- codespell: show version number in CI log.
- codespell: drop no longer needed word exception: `msdos`.
- codespell: include all curl source tree, except `packages` and
  `winbuild`. Drop an obsolete file exclusion.
- add new spellchecker job using the `typos` tool. It includes
  the codespell dictionary and a couple more. Use linuxbrew to install
  it. This takes 10 seconds, while installing via `cargo` from source
  would take over a minute.
- codespell: introduce an inline ignore filter compatible with `cspell`
  Make `typos` recognize it, too. Move single exceptions inline.

Fix new typos found. Also rename variables and words to keep
spellchecking exceptions at minumum. This involves touching some tests.
Also switch base64 strings to `%b64[]` to avoid false positives.

Ref: https://github.com/crate-ci/typos/blob/master/docs/reference.md
Ref: https://github.com/codespell-project/codespell?tab=readme-ov-file#inline-ignore
Ref: https://github.com/codespell-project/codespell/issues/1212#issuecomment-1721152455
Ref: https://cspell.org/docs/Configuration/document-settings

Closes #17905

.github/workflows/checksrc.yml

@@ -45,8 +45,8 @@ jobs:
       - name: 'check'
         run: scripts/checksrc-all.pl
 
-  codespell-cmakelint-pytype-ruff:
-    name: 'codespell, cmakelint, pytype, ruff'
+  spellcheck-cmakelint-pytype-ruff:
+    name: 'spellcheck, cmakelint, pytype, ruff'
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
@@ -61,20 +61,23 @@ jobs:
           sudo apt-get -o Dpkg::Use-Pty=0 update
           sudo rm -f /var/lib/man-db/auto-update
           sudo apt-get -o Dpkg::Use-Pty=0 install \
-            codespell python3-pip python3-networkx python3-pydot python3-yaml \
+            python3-pip python3-networkx python3-pydot python3-yaml \
             python3-toml python3-markupsafe python3-jinja2 python3-tabulate \
             python3-typing-extensions python3-libcst python3-impacket \
             python3-websockets python3-pytest python3-filelock python3-pytest-xdist
-          python3 -m pip install --break-system-packages cmakelang==0.6.13 pytype==2024.10.11 ruff==0.11.9
+          python3 -m pip install --break-system-packages cmakelang==0.6.13 pytype==2024.10.11 ruff==0.11.9 codespell==2.4.1
 
-      - name: 'spellcheck'
+      - name: 'codespell'
         run: |
-          codespell \
-            --skip scripts/mk-ca-bundle.pl \
-            --skip src/tool_hugehelp.c \
-            --skip scripts/wcurl \
-            -I .github/scripts/codespell-ignore.txt \
-            CMake include m4 scripts src lib
+          codespell --version
+          .github/scripts/codespell.sh
+
+      - name: 'typos'
+        run: |
+          /home/linuxbrew/.linuxbrew/bin/brew install typos-cli
+          eval "$(/home/linuxbrew/.linuxbrew/bin/brew shellenv)"
+          typos --version
+          .github/scripts/typos.sh
 
       - name: 'cmakelint'
         run: scripts/cmakelint.sh