Trim trailing slash in `--home` argument's value

# What's expected

Since in `acme.sh` path strings are concatenated with a hardcoded slash in between, the left operand must never end with a trailing slash for the resulting path to be valid. Otherwise, obviously, the resulting path will have two adjacent slashes in the middle and will not be valid.

# What actually happens

Even though I cannot tell for each of the input params, I know this for sure for the the `--home` argument's value.

If I run `acme.sh` with `--home` argument's value being a path ending in a trailing slash,

```sh
acme.sh ... --debug ... --home /some/path/ ... -d somedomainna.me ...
```

I get the following (distinct) occurrencies of resulting invalid paths containing two adjacent slashes:

```
[...] Using config home:/some/path/

[...] DOMAIN_PATH='/some/path//somedomainna.me'

[...] _CURL='curl --silent --dump-header /some/path//http.header  -L  -g '

[...] The domain key is here: /some/path//somedomainna.me/somedomainna.me.key

[...] _CURL='curl --silent --dump-header /some/path//http.header  -L  -g  -I  '

[...] Your cert is in: /some/path//somedomainna.me/somedomainna.me.cer

[...] Your cert key is in: /some/path//somedomainna.me/somedomainna.me.key

[...] The intermediate CA cert is in: /some/path//somedomainna.me/ca.cer

[...] And the full chain certs is there: /some/path//somedomainna.me/fullchain.cer

```

# Suggested fix

Trim trailing slash in `--home` argument's value from the get-go.

acme.sh

@@ -7496,7 +7496,7 @@ _process() {
       shift
       ;;
     --home)
-      export LE_WORKING_DIR="$2"
+      export LE_WORKING_DIR="${2%/}"
       shift
       ;;
     --cert-home | --certhome)